Abstract

The Islamic (Hijrī) calendar is the standard measure of time in the Qur’an and Sunnah,[1] and plays an integral role in the lives of Muslims. It is used for annual ritual worship such as paying the alms-tax (zakāh), fasting during the month of Ramadan, and performing the pilgrimage (ḥajj). While the Islamic calendar is actively used for religious purposes, its role as one of the cornerstones of Islamic identity has waned over time to the point that many Muslims are unaware of the current month, day, and year under the Hijrī system of dating. This paper aims to understand the historical development of the Hijrī calendar and to identify the factors that caused it to decline. The goals are to encourage reflection on the current state of the Muslim community (ummah), and to encourage the revival of the Hijrī calendar.

Defining the Islamic Calendar

Recently, the Crown Prince of Saudi Arabia, Muhammad bin Salman, chose to call his transformation plan for the country Vision 2030 rather than Vision 1451 (the corresponding Islamic year), which was surprising given the Kingdom’s long history of adhering to the Islamic calendar for both civil and religious matters. The Kingdom has used the Islamic calendar ever since the country was founded in 1932, but as part of Vision 2030 switched to the Gregorian calendar for determining the pay schedules of public sector employees in 2016, effectively increasing the workload by eleven days per year.[2] Other countries have followed suit and have begun to relegate the Islamic calendar to religious matters, detaching it from civil life. How did the land where the Islamic calendar was first established and remained in use for more than fourteen centuries come to such a decision? Why have so many Muslims become unaware of the months and years of the Islamic calendar? The purpose of this article will be to examine the history of the Islamic calendar, and to understand how its role as a marker of Islamic identity has diminished.
As we will see in more detail below, the Islamic calendar is a lunar calendar that plays an important role in the sanctification of time for Muslims. In order to gain a better understanding, it is helpful to understand the structure of the calendar and what distinguishes it from other calendars in use throughout history. To that end, we note that the Islamic calendar has three integral elements.
First, there are twelve lunar months in which every month is determined by the arrival of the new moon. These months are: Muḥarram (the first month of the year), Ṣafar, Rabīʿ al-Awwal, Rabīʿ al-Thānī, Jumādá al-Ūlá, Jumādá al-Thāniyah, Rajab, Shaʿbān, Ramaḍān, Shawwāl, Dhū al-Qaʿdah, and Dhū al-Ḥijjah. Allah says: 

Surely, the number of months ordained by Allah is twelve since the day He created the heavens and the earth.[3] 

In his exegesis of the Qur’an, al-Jāmiʿ li-aḥkām al-Qurʾān, Qurṭubī (d. 671 AH) states that Allah decreed and determined the twelve months the day He created the heavens and the earth, established and named these months, and revealed them to prophets in their revealed books.[4] The names and order of these months existed before Islam but were tampered with over time; however, it was according to Allah’s divine will that they would be recalibrated by the time the Prophet ﷺ gave his Farewell Sermon. The Prophet ﷺ said: “Time has come back to its original state which it had when Allah created the heavens and the earth.”[5] 
In addition, the Islamic lunar calendar runs ten to eleven days behind the Gregorian solar calendar yearly and as a result does not synchronize with the seasons, a feature that distinguishes it from the lunisolar Hebrew (Jewish) calendar, which offsets the difference every two or three years by inserting a 13th leap month to synchronize the lunar months with the seasons.[6] 
Second, the Islamic calendar contains four sacred months: Muḥarram, Rajab, Dhū al-Qaʿdah, and Dhū al-Ḥijjah. 
Allah says:

Surely, the number of months ordained by Allah is twelve since the day He created the heavens and the earth, of which four are sacred. That is the upright religion (al-dīn al-qayyim).[7]

Lastly, it is a marker of the migration (hijrah) of Prophet Muḥammad ﷺ from Mecca to Medina in 622 CE, which marks the beginning of the Islamic era, and is a fixed point from which the first year of the calendar (1 AH) has been determined.[8] Thus, another name given to it is the Hijrī calendar. 
Allah says:

He is the One Who has made the sun a radiant source and the moon a light, and precisely measured the lunar stations[9] so that you may know the number of years and how to calculate time (ḥisāb). Allah did not create this except with a purpose (ḥaqq). He makes the signs clear for people of knowledge.[10]

Expounding on ḥaqq, al-Qurṭubī (d. 671 AH) states: “Allah did not intend to create the moon except with wisdom and accuracy, as a means to display His creation and wisdom, as evidence for His will and knowledge, and to reward all those who follow it.”[11] Ibn ʿAṭīyah (d. 541 AH) defined al-dīn al-qayyim as “the law of God and following it.”[12] Thus, the scholars did not view use of the Islamic calendar merely as a tool to measure time, but also as a form of worship.

Sacred months

The second characteristic of the Islamic calendar is that it contains four sacred months, as Allah says:

Surely, the number of months ordained by Allah is twelve since the day He created the heavens and the earth, of which four are sacred. That is the upright religion. So do not wrong yourselves during these months and fight the associators all together, as they fight you all together, and be sure that Allah is with the God-fearing.[13]

In addition, the Prophet ﷺ said in his Farewell Sermon:

Time has come back to its original state which it had when Allah created the Heavens and the Earth. The year is twelve months, four of which are sacred. Three of them are in succession: Dhū al-Qaʿdah, Dhū al-Ḥijjah, Muḥarram, and [the fourth being] Rajab Muḍar[14] which stands between Jumādá [Thāniyah] and Shaʿbān.[15]

Numerous approaches have attempted to uncover the wisdoms behind the sanctity of the four sacred months, but at its core, sanctity stems from God’s divine choosing. Qatāda (d. 22 AH) surmises:

Allah glorifies whatever He wills. Allah chose a select few from His creation, chose certain angels and humans to be messengers, chose certain words to be mentioned, chose specific lands to be places of worship, chose the month of Ramaḍān [as the month to fast] and chose the sacred months… So glorify what Allah has glorified for things are only glorified because Allah has glorified them, [and this is understood] by those with acumen and intellect.[16] 

Understanding the wisdom behind what Allah has commanded helps the feeble human mind attain deeper appreciation; however, understanding the wisdom behind a particular command is not a prerequisite for the command to be obeyed. For example, there may be wisdoms for why we perform three rakʿah for the maghrib (sunset) prayer, but regardless of whether we understand those wisdoms, the responsibility of performing the prayer the way it has been mandated emanates from the command of the Prophet ﷺ, whom Allah ordered us to obey. Similarly, the sanctity of the sacred months comes from Allah’s divine choosing. A person may choose to express gratitude for this in different ways and extract various wisdoms as a means of motivation, but must be cautious not to claim these wisdoms as their reasons for obedience. Ultimately, glorifying the sacred months is part of obeying Allah’s commands, which is something we discuss in more detail below.
Three of the four sacred months are successive, namely Dhū al-Qaʿdah, Dhū al-Ḥijjah (the month during which the annual Ḥajj pilgrimage takes place), and Muḥarram. For the pre-Islamic Arabs, the Ḥajj pilgrimage was the beating heart of society and the annual epicenter for trade and information. Preserving its sanctity was of the utmost importance. Ibn Kathīr mentions that these three sacred months were consecutive to ensure safe travel to and from the Ḥajj. He also asserts that Rajab was sacred because those who traveled from afar could come earlier in the year to set up for the pilgrimage, and then leave at a later time safely. Protecting travelers to and from the Ḥajj was a priority, and any strife or bad blood amongst tribes was to be put on hold and resumed at a later date, which may be one of the wisdoms behind the prohibition of fighting during these months.[17]
The exegete Niẓām al-Dīn al-Nīsābūrī (d. 850 AH) mentions that the prohibition of fighting during the sacred months originated from Abraham which the pre-Islamic Arabs adopted in their traditions.[18] Whether there is evidence to prove this is unclear, but we can be certain that the prohibition against fighting during the sacred months existed before Islam, and was practiced by the pre-Islamic Arabs. 
The prohibition against fighting continued into the start of the Islamic era as Allah says: “Do not wrong yourselves during these months”[19] and “They ask you about fighting in the sacred month. Say: ‘Fighting in it is a grave [offense].’”[20] The majority of scholars are of the opinion that the prohibition of fighting in the sacred months was abrogated by the verse: “Fight the polytheists all together, as they fight you all together”[21] and the Prophet’s siege of Ṭāʾif during the sacred month of Dhū al-Qaʿdah. 
Moreover, we know from historical accounts dating back as early as the first century after the hijrah that the pious predecessors went on numerous expeditions and battles after the Prophet’s death during the sacred months, demonstrating their attitude towards the prohibition of fighting during the sacred months. Part of the Battle of Ṣiffīn[22] (37 AH) occurred in the month of Dhū al-Ḥijjah, the Battle of Karbalāʾ (61 AH) occurred in the month of Muḥarram, and the Battle of Ḥarrah (63 AH) occurred in the month of Dhū al-Ḥijjah.[23] 
Despite this, some have attempted to use the prohibition of fighting in the modern era for peace. For example, former Secretary-General of the United Nations, Ban Ki-moon, made an incorrect statement, most likely related to him by a Muslim who had little understanding of the sacred months, and perhaps innocently named Ramaḍān as one of the sacred months as part of a well-intentioned plea to end the fighting in Syria.

I have learned that the month of Ramaḍān is part of al-Ashhur al-Ḥurum, the four months during which wars are supposed to stop. For the sake of the Syrian people, therefore, I would like to call on all parties in Syria to respect this religious obligation for at least, at a minimum, one month.[24]

The sacred months are also a time for increasing good deeds, repenting, and avoiding sins. Sins committed in these months are weighed more heavily while good deeds are multiplied, an understanding that has played a role in Islamic jurisprudence. For example, the Shāfiʿī school of jurisprudence increases blood money (diyah) during the sacred months.[25] In addition, Māwardī (d. 450 AH) mentions that the emphasis on good deeds and sins during these sacred months is meant to prepare one for the rest of the year.[26]  In his Laṭāʾif al-Maʿārif, Ibn Rajab (d. 795 AH) mentions that it is encouraged to increase fasting during all of these months. In addition, he mentions unique benefits of each month, as detailed below:
Glorification can be expressed in a myriad of ways, the Prophetic way being superior. However, what is most important is that a Muslim not treat the sacred months as the rest of the year. To distinguish specific acts of worship, their intensity, and intentionality is to recognize Allah’s glorification of the sacred months. As for the narrative that the sacred months are significant mainly because of the prohibition of fighting they are associated with, this has been overstated. We need to transition from understanding the sacred months from a historical perspective to a devotional one moving forward.

Development of the Islamic Era

The third important characteristic of the Islamic calendar is that it marks the establishment of the Islamic era. The importance of the Islamic calendar was inculcated in the Prophet’s companions, who strongly adhered to the order and number of months, and would implement it in a more formal manner after the passing of the Prophet ﷺ. As the Islamic empire grew, legal rulings, deeds, and other important documents depended heavily on dates as a means of communication and preserving order. While the months and days of the calendar were well established, the companions still faced challenges in chronicling events on a yearly basis as it was unknown which year they were referring to when deeds and documents arrived with no complete date. In his historical chronicle, Tārīkh al-Rusūl wa-al-Mulūk, Ṭabarī (d. 310 AH) states:

Maymūn b. Mihrān (d. 117 AH) narrates: A legal document for a deed was delivered to ʿUmar which had the month of Shaʿbān written on it. ʿUmar asked: Is this the Shaʿbān of last year or this coming year? Then he said to the companions: Let us determine an epoch for the people to use.[30]

Throughout human history, people have used memorable events as reference points for establishing epochs. In his book, al-Muntaẓim fī Tārīkh al-Mulūk wa al-Umam, Ibn al-Jawzī (d. 597 AH) references al-Shaʿbī (d. 103 AH) summarizing that mankind’s first epoch was the descent of Adam, then the rescue of Noah from the flood, and then the cooling of the fire into which Abraham was thrown.[31] 
Moreover, the Scythian monk Dionysius Exiguus (d. 544 CE) introduced the Anno Domini (AD) dating system used for the Gregorian calendar. The name means “in the year of the Lord” which is based on counting years from the birth of Jesus as a starting point. Preceding that, the Romans would use the regnal years of emperors and the fifteen-year tax assessment cycle as their epochs.[32] 
Epochs were also used by the pre-Islamic Arabs. For example, they used the death of Kaʿb ibn Luʾayy,[33] the Year of the Elephant (ʿĀm al-Fīl),[34] and Ḥarb al-Fijār[35] as multiple epochs.[36] Additionally, the polymath al-Bīrūnī (d. 440 AH) states that each of the ten years during the Medinan Period of the Prophet ﷺ was appointed a unique name as a reference point.[37] 
        1st year: The Year of Permission (Sanat al-Idhn)
        2nd year: The Year of the Command of Fighting (Sanat al-Amr bi-al-Qitāl)
        3rd year: The Year of the Trial (Sanat al-Tamḥīṣ)
        4th year: The Year of Felicitation to Newlyweds (Sanat al-Tarfiʾah)
        5th year: The Year of the Earthquake (Sanat al-Zalzalah)
        6th year: The Year of Inquiring (Sanat al-Istiʾnās)
        7th year: The Year of Gaining Victory (Sanat al-ʾIstighlāb)
        8th year: The Year of Equality (Sanat al-Istiwāʾ)
        9th year: The Year of Exemption (Sanat al-Barāʾah)
        10th year: The Year of Farewell (Sanat al-Wadāʿ)
This system continued into the caliphate of ʿUmar b. al-Khaṭṭāb (d. 23 AH) until the companions came to a consensus on using the migration of the Prophet ﷺ as the starting point of the Islamic era. Ṭabarī mentions a few narrations that eventually led to the advent of the Islamic era:

Abū Mūsá ʿAbd Allāh b. Qays al-Ashʿarī (d. 50 AH) wrote to ʿUmar: Letters have come to us which have no date. ʿUmar then gathered his advisors. Some of them suggested using the revelation to the Prophet ﷺ as [the starting point of] the era. Others suggested basing it on the Prophet’s ﷺ migration. ʿUmar then replied: We will base it on the migration of the Prophet ﷺ, for the migration is what separated truth from falsehood.[38]

A man came to ʿUmar and said: Chronicle [events]. ʿUmar said: [How should we] chronicle? He replied: The way the foreigners write “in this month of this year.” ‘Umar agreed and asked: Which year shall we start from? Some suggested revelation while others suggested from the death of the Prophet ﷺ. They eventually agreed to use the migration as [the starting point of] the era. They then discussed which month to begin with. Some suggested Ramaḍān while others suggested Muḥarram because it was the month people departed from Ḥajj and was a sacred month. The companions then unanimously agreed to start the year with Muḥarram.[39]

We know with certainty that these discussions occurred during the caliphate of ʿUmar. We also know that choosing the migration as the starting point of the Islamic era was a matter of informed judgment (ijtihād), and that the companions came to a consensus on the matter. Thus, following the Islamic calendar involves not only obeying ﷺ Allah and His Messenger ﷺ, but also relying on the consensus of the companions in preserving Islamic identity. 
Despite this consensus, at least one attempt has been made in the modern era to change the starting point of the Islamic era. In the mid-19th century, Muammar Gaddafi created the Libyan calendar and arbitrarily changed the established starting point of the Islamic era from the year of the Prophet’s migration to the year of the Prophet’s death, ten years later.[40] 
American reporter Neil MacFarquhar reported on the chaos that ensued: “‘Why do we keep using different dates?’ bellowed a woman at the Popular Committee meeting. ‘Why can’t we be like every single other Muslim country and count from the time of the Prophet’s migration, not from his death? What is this?’ The unspoken answer was that Libya’s leader liked it that way.”[41]
By studying the migration as the starting point of the Islamic era—Anno Hegirae (AH) which means in the year of migration[42]—we can begin to ponder the lessons that the companions left for posterity. 
For the companions, the Prophet’s migration was the spiritual and physical establishment of the first Muslim community as John Esposito succinctly states:

The importance of the hijra is reflected in its adoption at the beginning of the Islamic calendar. Muslims chose to date their history from neither Muhammad’s birth nor his reception of the first revelation in 610 AH, but from the creation of the Islamic community (ummah). The community, as much as the individual, was to be the vehicle for realizing God’s will on Earth.[43]

In brief, the Islamic calendar is not merely a twelve-month lunar calendar with four sacred months, but also a marker of Islamic identity by virtue of the institutionalization of the first Muslim community 1442 years ago.

Nasīʾ

As the Islamic calendar began to play a larger role in Muslim identity and worship, ensuring it remained unaltered was vital. Any altering or manipulation of the calendar would have involved altering the command of Allah and His Messenger ﷺ, and detaching Muslims from their unique identity. Allah explicitly mentions the loathsome nature of tampering with the order and number of months:

Reallocating (nasīʾ) the sanctity of [these sacred] months is an increase in disbelief, by which the disbelievers are led astray. They adjust the sanctity one year and uphold it in another, only to maintain the number of months sanctified by Allah, violating the very months Allah has made sacred. Their evil deeds have been made appealing to them. And Allah does not guide the disbelieving people.[44]

Nasīʾ was the reallocation of sacred months for various motives. Ibn ʿAbbās (d. 68 AH), Abū Manṣūr al-Azharī (d. 370 AH), and others relate that the pre-Islamic Arabs would switch the month of Muḥarram with Ṣafar to avoid the perceived inconvenience of enduring three consecutive sacred months during which they were prohibited from fighting.[45] Others suggest that they would rename Muḥarram Ṣafar, resulting in two Ṣafars. Mujāhid (d. ca. 102 AH) states they would perform Ḥajj in the same unique month for two years at a time. For example, they would perform Ḥajj in the month of Dhū al-Hijjah for two years, then in the month of Muḥarram for two years, et cetera. However, there seems to be little evidence supporting this. Abū Mūsá al-Ashʿarī states that every two years they would add a 13th leap month to the calendar[46] while al-Bīrūnī (d. 440 AH) states that they would add a thirteenth leap month every three years to synchronize the lunar months with the seasons, also known as intercalation.[47] 
Based on the above, Muslim scholars have interpreted nasīʾ in two main ways: 1) as an intentional reallocation of sacred months, which the pre-Islamic Arabs used for political influence, and 2) as an incidental reallocation of sacred months due to the insertion of leap months, known as intercalation. Below is an illustration of the different interpretations of nasīʾ.

Nasīʿ used intentionally for political influence

It is difficult to imagine a society in which dates are unknown to the masses or altered. Our lives have been carefully constructed and augmented by the modern calendar, and with globalization, any change would cause widespread pandemonium. However, it was commonplace for calendars to be used as a tool for power and manipulation throughout history.
For example, the Roman calendar contained a list of dies fasti, sanctioned dates on which governing and societal organizations would conduct business. These dates were not available to the public; rather, they were controlled by Roman kings and the aristocratic patrician class. For the first few centuries during which records were kept, the priests and aristocrats kept the calendar a secret among themselves, which gave them an advantage over the commoners in conducting business and controlling the religious and social structure that governed Roman life.[48]
In the Arabian Peninsula, the Banū Kinānah were an influential Arab tribe responsible for the fair of Majanna, the worship of the idol ʿUzzá, and determining the reallocated months (nasīʾ).[49] They would appoint a person with the title of Qalammas whose job it was to implement the reallocation of months during the Ḥajj season. As various tribes were departing from Miná during the rituals of Ḥajj, the Qalammas would say: “I am the one whose decision will not be overturned!” The Arabs would then approach him and say: “Postpone Muḥarram and replace it with Ṣafar!”[50] He would then switch the months, and those who had come to Mecca for the Ḥajj would go back to their homes and inform their families of the change.[51] This great responsibility the Banū Kinānah had inherited gave the tribe’s members political influence in conducting trade and fairs, and allowed them to control the cycle of pilgrimages and influence tribal wars. So great was their influence that any threat to their authority would result in retaliation.
To illustrate this point, some historians go as far to suggest that Abrahah’s expedition to destroy the Kaʿbah during the Year of the Elephant (ʿĀm al-Fīl) was motivated by the inconvenience of the Ḥajj season coinciding with Easter due to intercalation, particularly because Abrahah had built the church to divert them from the Ḥajj in Mecca.[52] Because the lunar calendar used by the Arabs was intercalated, however, the annual Ḥajj pilgrimage fell during the same time as Easter each year, effectively reducing the number of pilgrims to his church. He wrote of his intentions to destroy the Kaʿbah to the Negus, the Abyssinian king. A man from the tribe of Banū Kinānah intercepted the message and in response defiled the church. For the people of Banū Kinānah, Abrahah’s intentions were not only a threat to the Kaʿbah, but also a threat to their political influence over the calendar. The historian Hideyuki Ioh states: “Maintaining order among the Arab tribes in the pre-Islamic period depended on maintaining the cycle of pilgrimages, and Abrahah’s expedition was intended to change this traditional system unilaterally. The calendar adjuster’s reaction [defiling the church] can be understood as stemming from his role of controlling the cycle of pilgrimages all over the peninsula.”[53] Thus, maintaining power over the calendar allowed certain tribes and individuals to hold political influence in the Arabian Peninsula. 
In the wake of this unstable political scene, Islam institutionalized systems of justice. One of these institutions involved computing the months through the sighting of the moon. The emphasis in today’s Muslim communities over the method of moon sighting versus calculation has been debated ad nauseam and to some degree reduced certain months such as Ramaḍān to a cause célèbre. While there is certainly merit in discussing the juristic details of moon sighting and its proper implementation, this can at times overshadow the greater wisdom of establishing justice. With Banū Kinānah holding a tight grasp over the calendar, the Islamic ruling of moon sighting redistributed the responsibility to the masses. It acted as a divine system of checks and balances, as the moon cannot be hidden from the masses, it is observed by all, and it prevents those in power from exploiting and monopolizing the calendar. As long as just, sane, adult Muslims bear witness that they have seen the moon, the ruler is to take their testimony into account. Islam does not forgo authority, but it brilliantly provides a natural checks and balances system that is often forgotten.
In addition, physically sighting the moon (a tradition practiced by the pious predecessors) may have biological benefits, a possible wisdom that needs more study. Just as our bodies are biologically dependent on the sun for our circadian rhythm, the moon helps regulate the circalunar and circa semilunar rhythms, which has effects on sleep, mood, birth rates, and the reproductive cycles of certain species.[54] 
The Islamic calendar is a complex system in which many wisdoms of God are embedded, some apparent and some hidden. As Qurṭubī said:“Allah did not intend to create the moon except with wisdom and accuracy.”[55] Just as Allah created balance between the celestial bodies, the lunar calendar balances the scale in how we organize time, worship, and maintain justice in communities. 

Nasīʿ used incidentally as a means of imitation

The lunar calendar falls ten to eleven days behind the solar calendar every year, which results in the seasons desynchronizing with the lunar months. To adjust for this, the pre-Islamic Arabs would add a thirteenth month to the calendar every two or three years, also known as intercalation. One reason to believe that the pre-Islamic Arabs were intercalating is shown by the names of the months. For example, the month of Ramaḍān was an epithet for scorching heat, and the month of Jumādā for water freezing.[56] Thus, the fact that lunar months were named based on seasonal weather suggests that the practice of intercalation was being implemented before the months were first named. 
Another motivating factor for using intercalation was that it provided ease in scheduling of fairs and for harvesting crops. Hideyuki Ioh aptly states: “In pre-Islamic Arabia, a cycle of fairs going around the Peninsula clockwise had been established as being the most favorable for trade. Therefore, we may conclude that the 12-month lunar calendar was adjusted periodically by inserting a leap month to ensure the fairs occurred in the proper seasons.”[57]
One might wonder how the pre-Islamic Arabs learned to intercalate. Al-Bīrūnī states that “they learned intercalation from Jewish people in the area.”[58] As the Jews migrated to the Arabian Peninsula, they brought along their calendar which employed a complex mechanism for intercalation by incorporating a thirteenth month into the third, sixth, eighth, eleventh, fourteenth, seventeenth, and nineteenth years of a nineteen-year cycle. Observing the Jews, the Arabs attempted to reproduce this, but their efforts resulted in an unrefined intercalation. The addition of the thirteenth month incidentally altered the order of the sacred months, especially the month of Muḥarram, but was not necessarily an attempt to circumvent the prohibition against fighting. While intercalation provided ease to the pre-Islamic Arab lifestyle, at its core was an attempt to imitate the Jewish calendar. As we will soon see, Islam was averse to this type of imitation (tashabbuh). 
As described above, there are two main understandings of nasīʾ, which was practiced by the pre-Islamic Arabs for both political purposes and the use of intercalation which was motivated by convenience wrapped under imitation rather than political gain. While it is valuable to understand both types of nasīʾ in order to attain a more nuanced understanding of the Islamic calendar and its benefits to society, I would argue that the type of nasīʾ that is of more relevance to today’s Muslims is the nasīʾ that was practiced for convenience in imitation of the Jews. That is because if Muslims are unaware of the historical development of calendars, it could result in imitating other calendars unknowingly and the gradual loss of the Islamic calendar. Thus, any attempt to imitate other foreign calendrical elements, when identified, should be strongly condemned. Does this mean that using the Gregorian calendar alongside the Islamic calendar is prohibited? In order to understand this, we need to define the boundaries of impermissible imitation and its details.
Islam came with a number of new practices that were distinct from those of the Jews. For example, the direction of prayer (qiblah) was changed from Jerusalem to Mecca, and Friday was designated as Islam’s holy day. Additionally, the Prophet ﷺ said: “Whoever imitates (tashabbah) a people is from among them.”[59] The Damascene scholar, Najm al-Dīn al-Ghazzī (1061 AH), categorizes imitation (tashabbuh) into two types. First, if an act of devotion is both legislated and active (non-abrogated) for both Muslims and the people of the Book (i.e., Jews and Christians), then the attributes (waṣf) of that act of devotion must differ. For example, both Muslims and Jews fast on the Day of ʿĀshūrāʾ, but the Prophet ﷺ told the Muslims to fast the day before as well so that their fasting would differ from that of the Jews. Second, if the act of devotion found with the people of the Book has been abrogated by Islam, then any participation in the act is considered to be impermissible imitation regardless of any changes in attributes (waṣf). An example of this would be praying toward Jerusalem despite following the procedures for Islamic prayer.[60]  
The discussion surrounding the imitation of foreign calendrical elements falls under the first type of tashabbuh mentioned by al-Ghazzī.[61] Currently, the months and religious holidays associated with the Islamic calendar have remained unaltered. Thus, as long as the Islamic calendar can be distinguished from other calendars without any type of change or alteration, then it is difficult to prove that using the Gregorian calendar adjacent to the Islamic calendar constitutes impermissible imitation. However, the heavy reliance on the Gregorian calendar in recent times has led Muslims to become less knowledgeable about the Islamic calendar resulting in the very consequences feared from impermissible imitation. Even the early scholars were well aware of any underlying precursors that detached the Islamic calendar from the focal point of Muslim life and would speak vociferously against it. For example, Ibn Taymiyyah states in Iqtiḍāʾ al-Ṣirāṭ al-Mustaqīm: “Regarding naming months with foreign names, Abū Muḥammad al-Kirmānī (280 AH)[62] said: “I said to Aḥmad b. Ḥanbal (241 AH): ‘[Did you know] the Persians have days and months that they call by names that are not known?’ Aḥmad extremely despised this.”[63] 
This degradation of the Islamic calendar is also no stranger to Muslim countries in the modern era. For example, the Ottoman Empire at its inception standardized the Islamic calendar, but by the seventeenth century the treasurer, Hasan Pasha, suggested implementing the Julian calendar for fiscal matters as a way to accommodate the surrounding countries. By the mid-nineteenth century, after the Tanzimat reforms,[64] it became the official calendar for all civic matters. Following the empire’s defeat in World War I and the Treaty of Sèvres, the Islamic calendar lost its validity with the implementation of the “Changing the Inception of the Calendar” law on December 26, 1925, which is when the Gregorian calendar was officially adopted for use in the new Republic of Turkey.[65]
As mentioned earlier, the Crown Prince of Saudi Arabia, Muhammad bin Salman, chose to call his transformation plan for the country Vision 2030 which switched to the Gregorian calendar for paying public sector employees in 2016.  Relegating the Islamic calendar to religious purposes while using the Gregorian calendar for civil matters has been a popular approach by many Muslim-majority countries facing difficulties in balancing religious devotion and globalization. 
Is there a resemblance between the Muslim-majority countries and the Ottoman empire relegating the Islamic calendar to religious matters and detaching it from civil life? Does this forecast the demise of Muslim-majority countries just as the Ottoman empire faced in the early 20th century? A claim that broad would need extensive research. However, it is within reason to posit that the stability and preservation of Islamic identity within an Islamic empire or country, if one truly exists, is closely tied to the standardization of the Islamic calendar which regulates its affairs. 
Post-World War I, the Islamic calendar faced a severe casualty in the diaspora of the Muslim community, an unfortunate development that was espoused by Muslim politicians who were intimidated by colonizers imposing the Gregorian calendar on the countries they occupied. As Ibn Khaldūn states in his Muqaddimah: “The vanquished always want to imitate the victor in his distinctive mark(s), dress, occupation, and all his other conditions and customs.”[66] By linking imitation as an underlying motive for nasīʾ, the average Muslim can begin to recognize the implications of any foreign elements influencing or weakening the Islamic calendar and its lived experience, as Allah attributed disbelief (kufr) to nasīʾ. Among other things, this understanding may help one provide a more clear response to Muslims who do not understand why the Islamic calendar should be used outside of Ramaḍān, Ḥajj, Zakāh, the Eid holidays, and other religious occasions with religious significance. Most importantly, it contextualizes a nuanced explanation to Muslims living in a post-colonized world unaware of its history.

Conclusion

The Gregorian calendar has become an integral part of global communication. Discarding and replacing it would prove to be a difficult challenge and could possibly cause more harm than good. Yet, the Muslim community still has the autonomy to consciously influence how to communicate within its own spheres of activity. Mosques in the United States and elsewhere may wish to date their newsletters with the Gregorian and Islamic (Hijrī) dates side-by-side. Beginning sermons with the Islamic date can quickly educate communities, while the presence of Islamic calendars in homes, offices, and schools can help remind people of the relevant date on a daily basis. In other words, any article of communication within the Muslim community should be standardized with the Islamic date as a stepping stone in reviving the Islamic calendar as a lived experience in the lives of Muslims. Lastly, organizing our lives around the Islamic calendar is not simply another way to schedule time, but also an expression of our worship of Allah.
Allah knows best. 

Acknowledgments

This article has benefited greatly from Dr. Samuel Ross, Shaykh Ismail Kamdar, Mufti Muntasir Zaman, and Dr. Tahir Wyatt. Their reading and commentary of this article helped refine the message I attempted to relay and elucidate the arguments. I would like to thank Dr. Jonathan Brown for encouraging me in writing this paper when I approached him with the topic. I would like to also thank Dr. Nameera Akhtar and Amel Abdullah for their meticulous editing. Lastly, I would like to thank Dr. Omar Suleiman and the Yaqeen team for their support and assistance throughout the process. 

Notes

[1] The generally approved standard or practice introduced by the Prophet ﷺ.
[2] Alexandra Sims, “Saudi Arabia Switches to ‘Western’ Gregorian Calendar So It can Pay Workers Less and Save Money,” Independent, December 17, 2016, https://www.independent.co.uk/news/world/middle-east/saudi-arabia-calendar-gregorian-switches-pay-workers-less-save-money-a7342331.html.
[3] Qur’an 9:36.
[4] Al-Qurṭubī, al-Jāmiʿ li-aḥkām al-Qurʾān (Cairo: Dār al-Kutub al-Miṣrīyah, 1964), 10:455.
[5] F. C. De Blois, “Taʾrīkh”: I.1.iv. “Pre-Islamic and Agricultural Calendars of the Arabian Peninsula,” in The Encyclopaedia of Islam, 2nd ed. (Leiden: Brill, 1955–2005), 10:260.
[6] The Islamic calendar was not the first lunar calendar. The Hebrew calendar, also called the Jewish calendar, was a lunisolar calendar that incorporated a thirteenth month into a nineteen-year cycle, at intervals oscillating between two and three years. See: Jere Bacharach, A Middle East Studies Handbook (Seattle: University of Washington Press, 1984) 9; also see: Hideyuki Ioh, “The Calendar in Pre-Islamic Mecca,” Arabica 61 (2014): 498–500.
[7] Qur’an 9:36. Allah refers to the lunar calendar as purpose (ḥaqq) and the upright religion (al-dīn al-qayyim), words typically used in reference to the Qur’an, God (Allah), and belief, pointing to the calendar’s significance. See:  Qur’an 43:30, 10:32, and 12:40.
[8] There is no Year Zero.
[9] Lunar stations, also known as lunar mansions, are a segment of the ecliptic through which the moon passes in its orbit around the earth. The traditional Arab astrological system consisted of twenty-eight stations, and each station lasted approximately thirteen days. These stations were grouped together and associated with a specific constellation and zodiac sign. See: William Matthew O’Neil, Time and the Calendars (Manchester: Manchester University Press, 1976), 53; also see: Amel Durakovic, “Celestial Lessons – Amel Durakovic – Session 1: Motion of the Heavenly Bodies,” Cambridge Muslim College, YouTube video, April 26, 2020, https://www.youtube.com/watch?v=MZ-2zKMEFs8.
[10] Qur’an 10:5. Ibn Rajab (d. 795 AH) comments that the moon has been used to calculate the years, while the sun has been used to calculate the days and weeks, together completing the method of calculating time (ḥisāb). Ibn Rajab, Laṭāʾif al-maʿārif (Beirut and Damascus: Dār Ibn Kathīr, 1999), 38.
[11] Al-Qurṭubī, al-Jāmiʿ li-aḥkām al-Qurʾān, 10:455.
[12] Al-Qurṭubī, 10:198.
[13] Qur’an 9:36.
[14] The scholars mention that the reason for the Prophet ﷺ saying “Rajab Muḍar, which stands between Jumādā [Thāniya] and Shaʿbān” was because Ramaḍān was known as Rajab Rabīʿa during the times of jāhilīyah. In order to avoid confusion, he ﷺ mentioned Rajab Muḍar, which is between Jumādā (Thāniya) and Shaʿbān, as opposed to Ramaḍān (Rajab Rabīʿa), which is between Shaʿbān and Shawwāl. In summary, there were two Rajabs: Rajab Muḍar (the current Rajab) and Rajab Rabīʿa (Ramaḍān). See: Jawād ʿAlī, al-Mufaṣṣal fī tārīkh al-ʿArab qabl al-Islām (Beirut: Dār al-Sāqī, 2001), 6:117.
[15] Bukhārī, Ṣaḥīḥ al-Bukhārī, kitāb tafsīr al-Qurʾān, 6:66, no. 4662.
[16] Al-Qurṭubī, al-Jāmiʿ li-aḥkām al-Qurʾān, 10:89.
[17] Ibn Kathr, Tafsīr al-Qurʼān al-ʿAẓīm (Beirut: Dār al-Ṭayyiba lil-Nashr wa-al-Tawzīʿ, 1999), 4:130.
[18] Al-Nīsābūrī, Gharāʾib al-Qurʾān wa-raghāʾib al-Furqān (Beirut: Dār al-Kutub al-ʿIlmiyyah, 1996), 3:463 
[19] Qur’an 9:36. Qatāda (d. 22 AH) interprets these months as being the sacred months, while Ibn ʿAbbās (d. 68 AH) understood the verse to be referring to all twelve months in general. Ibn al-Jawzī, Zād al-Masīr (Beirut: Dār Ibn Ḥazm, 2002), 2:257.
[20] Qur’an 2:217.
[21] Qur’an  9:36.
[22] Al-Ṭabarī, Tārīkh al-rusūl wa-al-mulūk (Cairo: Dār al-Maʿārif bi Miṣr, 1967), 4:574.
[23] Others argue that the Prophet ﷺ did not fight the people of Ṭāʾif in the month of Dhū al-Qaʿdah but just set up a post there during the month. Ibn Rajab, Laṭāʾif al-Maʿārif (Beirut: Dār Ibn Kathīr, 1999), 224–25.
[24] Ban Ki-moon, “Secretary-General’s Ramadan Appeal for the People of Syria,” United Nations, accessed March 18, 2021, https://www.un.org/sg/en/content/sg/statement/2013-07-08/secretary-generals-ramadan-appeal-people-syria.
[25] Ibn Kathīr, Tafsīr al-Qurʾān al-ʿAẓīm, 4:130.
[26] Al-Māwardī, al-Nukat wa-al-ʿuyūn (Beirut: Dār al-Kutub al-ʿIlmiyya, 1999), 2:360.
[27] The most excellent fast after [fasting] in the month of Ramaḍān is the fast in the month of Muḥarram.
Muslim, Ṣaḥīḥ Muslim, kitāb al-ṣiyām, 2:321, no. 1163.
[28] Ibn Taymiyya, Iqtiḍāʾ al-ṣirāṭ al-mustaqīm (Riyāḍ: Dār al-Ishbīlyā, 1998), 2:134. "اللهم بارك لنا في رجب وشعبان وبلغنا رمضان"
[29] ʿAtīra was an animal sacrifice in pre-Islamic Arabia, consisting of a sheep, a goat, or a camel. The ʿatīra sacrifice was performed during the first ten days of Rajab. The Shāfiʿī school views this as recommended, while the majority say it has been abrogated. Jan Retsö, “ʿAtīra,” in Encyclopaedia of Islam, 3rd ed. (Leiden: Brill, 2007).
[30] Retsö, 388–89.
[31] Abū al-Faraj ibn al-Jawzī, al-Muntaẓim fī Tārīkh al-Mulūk wa al-Umam (n.p.: Dār al-Kutub al-ʿIlmiyyah, 1995), 4:226
[32] Encyclopedia Britannica Online, s.v. “History of Europe,” accessed March 18, 2021, https://www.britannica.com/topic/history-of-Europe.
[33] The eighth forefather of Prophet Muḥammad ﷺ.
[34] The year in which Abraha al-Ashram was defeated in Makkah, which is the same year in which Prophet Muḥammad ﷺ was born.
[35] The name of a war waged toward the end of the sixth century CE during the holy months that took place between the tribes of Quraysh and Banū Kināna on one side and the tribes of Qays-ʿAylān (without the Ghaṭafān) on the other.
[36] Ibn al-Jawzī, al-Muntaẓim, 4:227.
[37] Al-Bīrūnī, ʾĀthār al-Bāqiya [Vestiges of the past] (London: W.H. Allen, Pub. for the Oriental translation fund of Great Britain & Ireland, 1879), 35.
[38] Al-Ṭabarī, Tārīkh al-rusul wa-al-mulūk, 2:390.
[39] It is also mentioned that ʿUbayd b. ʿUmayr said: “Muḥarram is the month of Allah. It is the first month of the year. It is the month when the Kaʿba is garbed, the month in which dates are recorded, and taxes are enforced. It is the month which has a day when mankind repents to Allah and Allah accepts their repentance.” Al-Ṭabarī, 389–90.
[40] Ross Marlay, “Qaddafi, Muammar,” in The Encyclopedia of the Developing World (London: Routledge, 2006), 1338.
[41] Neil MacFarquhar, The Media Relations Department of Hizbollah Wishes You a Happy Birthday: Unexpected Encounters in the Changing Middle East (New York: PublicAffairs, 2009), 38.
[42] Commonly mistaken as “After the Hijrah.”
[43]John L. Esposito, Islam: The Straight Path, rev. 3rd ed. (New York: Oxford University Press, 2005), 8.
[44] Qur’an 9:37.
[45] Al-Qurṭubī, al-Jāmiʿ li-aḥkām al-Qurʾān, 8:137.
[46] Al-Ṭabarī, Tārīkh al-rusūl wa-al-mulūk, 14:249.
[47] Hideyuki Ioh, “Calendar in Pre-Islamic Mecca,” 485.
[48] David Ewing Duncan, Calendar: Humanity’s Epic Struggle to Determine a True and Accurate Year (New York: HarperCollins, 1999), 30.
[49] Ioh, “Calendar in Pre-Islamic Mecca,” 487.
[50] Al-Qurṭubī, al-Jāmiʿ li-aḥkām al-Qurʾān, 8:137.
[51] This account also sheds light on why the month of Muḥarram, which is the first month on the Islamic calendar, is also the most tampered with. This is likely because Muḥarram provided a prime opportunity right after the Ḥajj pilgrimage to spread news of any changes to the calendar across the Arabian Peninsula as compared to other months.
[52] Uri Rubin, “The Great Pilgrimage of Muḥammad: Some Notes on Sūra IX,” Journal of Semitic Studies 27, no. 2 (1982): 244.
[53] Ioh, “Calendar in Pre-Islamic Mecca,” 485
[54] Studies on circalunar rhythms of conception or birth rates extend to humans, where the lunar cycle has been suggested to also affect sleep and mental health. While these reports remain controversial, factors like the increase in “light pollution” from artificial light might contribute to any discrepancies between studies (see: Florian Raible, Hiroki Takekata, and Kristin Tessmar-Raible, “An Overview of Monthly Rhythms and Clocks,” Frontiers in Neurology 8, May 2017, https://doi.org/10.3389/fneur.2017.00189). We also find that the Prophet ﷺ recommended performing wet cupping therapy (ḥijāma) on either the seventeenth, nineteenth, or twenty-first of every lunar month. Sunan Abū Dāwūd, no. 3861.
[55] Al-Qurṭubī, al-Jāmiʿ li-aḥkām al-Qurʾān, 10:198.
[56] Edward William Lane states: “The two months to which it is applied being [said to be] so called because, when the months were named, these two fell in the season of the freezing of water: (ISd, L, Mṣb:) [but this derivation seems to have been invented when the two months thus named had fallen back, into, or beyond, the winter; for when they received this appellation, the former of them evidently commenced in March, and the latter ended in May; therefore I hold the opinion of M. Caussin de Perceval, that they were thus called because falling in a period when the earth had become dry and hard by reason of paucity of rain, from jamādun, an epithet applied to land upon which rain has not fallen, or from jumādā, an epithet applied to an eye that sheds few tears.” See: Edward William Lane and Stanley Lane-Poole, “Jumādā,” in Arabic-English Lexicon (New York: F. Ungar Pub. Co, 1955); also see: Ibn Kathīr, Tafsīr al-Qurʾān al-ʿAẓīm, 4:146–47.
[57] Ioh, “Calendar in Pre-Islamic Mecca,” 477.
[58] Ioh, 485.
[59] Abū Dāwūd al-Sijistānī, Sunan Abū Dāwūd (Cairo: al-Risālah al-ʿĀlimiyyah, 2009), 6:5144, no. 4031. 
[60] Najm al-Dīn al-Ghazzī, Ḥusn al-tannabbuh li-mā warada fī al-tashabbuh (Beirut: Dār al-Nawādir, 2011), 7:298.
[61] I am assuming that the Gregorian calendar is associated with Christianity based on their epoch, which refers to the birth of Jesus. I am aware that the CE abbreviations have been used referring to the Common Era as a way to secularize the calendar; however, for the purpose of this argument, I made the assumption that the Gregorian calendar is the calendar of the Christians.
[62] Also known as Ḥarb b. Ismāʿīl al-Kirmānī. He was a student of Aḥmad ibn Ḥanbal.
[63] Ibn Taymiyya, Iqtiḍāʾ al-ṣirāṭ al-mustaqīm, 1:518.
[64] The Tanzimat reforms promulgated in the Ottoman Empire between 1839 and 1876 under the reigns of the sultans Abdulmecid I and Abdulaziz. These reforms, heavily influenced by European ideas, were intended to effectuate a fundamental change of the empire from the old system based on theocratic principles to that of a modern state.
Encyclopedia Britannica Online, s.v. “Tanzimat,” accessed March 18, 2021, https://www.britannica.com/event/Tanzimat.
[65] Safiye Kıranlar, “Even the Calendar Changes in Modern Times: The Story of the Calendar from the Ottomans to the Republic 1840–1945,” International Journal of Turcologia 6 (2008): 39–60.
[66] Ibn Khaldūn and Franz Rosenthal, The Muqaddimah: An Introduction to History (Princeton, NJ: Princeton University Press, 1967), 196.