Hazrat Umar (ra) Establishes the Hijri Calendar
With regard to how the Hijri calendar was established, there is a narration of Sahih Bukhari, which states that Hazrat Sahlra bin Saad reported that the companions did not start the calendar from the time of the advent of the Holy Prophet (sa) and nor from his demise, in fact, they started it from when the Holy Prophet (sa) arrived in Medina, i.e. after his migration.
(Al-Farooq, Shibli Naumani, p. 233, Idaara Islamiyyat, Karachi, 2004)
A commentator of Bukhari, Allama Ibn Hajar Al-Asqalani states that according to Imam Suhaili, “The companions decided to start the calendar from the migration [of the Holy Prophet (sa)] based on the following words of Allah the Almighty:
لَمَسْجِدٌ اُسِّسَ عَلَی التَّقْوٰی مِنْ اَوَّلِ يَوْمٍ
“‘A mosque which was founded upon piety from the very first day […]’.
(Ch.9: V.108)
“Thus, the meaning of ‘from the very first day’ would be the day the Holy Prophet (sa) and his companions arrived in Medina; however, Allah has the best of knowledge.”
There are various narrations with regard to why there was a need to start the Hijri calendar. Hazrat Abu Musa (ra) wrote to Hazrat Umar (ra) and stated that they would receive letters from him, but it did not have any date on them. Upon this, Hazrat Umar (ra) gathered the people to seek consultation on this. Allama Ibn Hajar states that in Bukhari, under the Book of Etiquettes, Hakim has related from Maimoon bin Mehran that once, a cheque was presented to Hazrat Umar (ra) which was only valid until Sha‘ban. Upon this, Hazrat Umar (ra) stated, “Which Sha‘ban does this refer to? The one that has passed, or the one that we are currently passing through, or the one to come?” Following this, Hazrat Umar (ra) stated that they should form a calendar which everyone could remember.
Ibn Sirin relates that once, a person came from Yemen and mentioned that he had observed that in Yemen, they had something which they referred to as a calendar and they wrote down the particular year and the month. Upon this, Hazrat Umar (ra) stated that this was an excellent method and they should write it down like that as well.
There are various narrations in regard to who started the Hijri calendar. According to one of the narrations, it was the Holy Prophet (sa) who instructed to note down the dates and this began from the month of Rabi‘ al-Awal. Hakim has written in his book, Al-Aqlil that it has been narrated by Ibn Shihab Zuhri:
اَنَّ النَّبِيَّ لَمَّا قَدِمَ الْمَدِيْنَةَ اَمَرَ بِالتَّارِيْخِ فَكُتِبَ فِي رَبِيْعِ الْاَوَّلِ
That is, “When the Holy Prophet (sa) arrived in Medina, he instructed for the dates to be written down and this began from the month of Rabi‘ al-Awal.” Allama Ibn Hajar states that this narration is “mu‘dal”, which means that it has two or more narrators missing one after the other in its chain of narrators.
According to another narration, a calendar began to be formally written down after the Holy Prophet (sa) migrated to Medina. However, the more commonly known narration is contrary to these aforementioned narrations and states that the Hijri calendar started from the time of Hazrat Umar (ra).
The author of Subul Al-Huda Wa Al-Rishad Fi Sirat Khair Al-Abad, Muhammad bin Yusuf Salehi states that Ibn Salaa states that he read in the book, Al-Shuroot by Abu Tahir Ma‘mish that the Holy Prophet (sa) instructed for the dates to be written down because when the Holy Prophet (sa) intended to send letters to the Christians in Najran, he instructed Hazrat Ali (ra) to write:
لِخَمْسٍ مِّنَ الْهِجْرَةِ
That is, “Five years after the Hijrah.” Thus, in light of this, it was the Holy Prophet (sa), who was the first to write down the dates and Hazrat Umar (ra) followed this practise of the Holy Prophet (sa).
According to another narration, it was Hazrat Ya‘la bin Umaiyyah, who was from Yemen, who started the practice of writing down the dates. Imam Ahmad has narrated this but the chain of narrators is broken between Amr and Ya‘la.
According to the third narration, which is more commonly known, the Hijri calendar began in the era of Hazrat Umar’s (ra) Khilafat.
There are further details mentioned in relation to why the Hijri calendar began from the year of migration.
When Hazrat Umar (ra) sought consultation with regard to forming a yearly calendar, one of the suggestions was that it should start from the year of the Holy Prophet’s (sa) birth. Another suggestion was that it should start from the year he was commissioned as a prophet. And the third suggestion was that it should start from the year in which the Holy Prophet (sa) passed away. The fourth suggestion was that it should start from the year in which the Holy Prophet (sa) migrated [to Medina]. It was ultimately decided to start from the year of migration because there was a difference of opinion in regard to the exact year in which the Holy Prophet (sa) was born and the year he was commissioned as a prophet. The reason why they did not start it from the year in which the Holy Prophet (sa) passed away was because this had an element of grief and sorrow for the Muslims due to the Holy Prophet’s (sa) demise. Hence, the companions all agreed to start from the year of migration. The companions started the year from the month of Muharram instead of Rabi‘ al-Awal because the Holy Prophet (sa) had decided to migrate in the month of Muharram. The Second Bai‘at at Aqabah had taken place in the month of Dhul-Hijjah and this was what eventually led to the migration. Thus, the first lunar month which appeared after the Second Bai‘at at Aqabah and the Holy Prophet (sa) having decided to migrate was Muharram and therefore, it was deemed appropriate to begin the year with Muharram.
Allama Ibn Hajar states that to start the Islamic calendar from the month of Muharram was the strongest argument in his view.
(Fathul Bari, Ibn Hajar, pp. 314-315, Hadith 3934, Dar-ul-Riyan Al-Turath, Cairo, 1986) (Subul Al-Huda Wa Al-Rishad, Vol. 12, pp. 36-37, Dar-ul-Kutub Al-Ilmiyyah Beirut, 1993)
There are various opinions in relation to when the Holy Prophet (sa) arrived in Madinah. The Holy Prophet (sa) would stop at different locations on the way and arrived close to Medina in 12 Rabi‘ al-Awal in 14 Nabwi/20 September 622 CE. According to some historians, the Holy Prophet (sa) arrived in 8 Rabi‘ al-Awal and there are some who state that the Holy Prophet (sa) left in the month of Safar and arrived in Rabi‘ al-Awal. The Holy Prophet (sa) left Mecca on the first of Rabi‘ al-Awal and arrived in Medina on 12 Rabi‘ al-Awal.
(Sirat Khatam Al-Nabiyeen, p. 23) (Sharah Al-Zarqani, Vol. 2, p. 102, Dar-ul-Kutub Al-Ilmiyyah, Beirut 2012) (Al-Farooq, Shibli Naumani, p. 248, Idaara Islamiyyat, Karachi, 2004)
There are also various narrations in regard to when the Hijri calendar was established. According to some, it was in 16 AH, but we also find mention of 17 AH, 18 AH and 21 AH as well.
(Fathul Bari, Ibn Hajar, Vol. 7, p. 315, Hadith 3934, Dar-ul-Riyan Al-Turath, Cairo, 1986) (Al-Kaafi Fi Al-Tarikh, Ibn Athir, Vol. 1, p. 13, Dar-ul-Kitab al-Arabi, Beirut, 2012) (Al-Farooq, Shibli Naumani, p. 248, Idaara Islamiyyat, Karachi, 2004)
In any case, most of the people agree that the calendar was established during the era of Hazrat Umar (ra).