Muhammad’s first revelation was an event described in Islamic tradition as taking place in AD 610, during which the Islamic prophet, Muhammad was visited by the angel Jibrīl, known as Gabriel in English, who revealed to him the beginnings of what would later become the Qur’an. The event took place in a cave called Hira, located on the mountain Jabal an-Nour, near Mecca. According to Mubarakpuri, the exact date of this event was Monday, the 21st of Ramadan just before sunrise, i.e. August 10, 610 C.E. – when Muhammad was 40 lunar years, 6 months and 12 days of age, i.e. 39 solar years, 3 months and 22 days.
Muhammad was born 55 days after the incident of the elephant, which occurred in the middle of Muharram 570 – i.e. his birth date was Monday, 12 Rabi’I in that year. Many military campaigns occurred around the turn of the year, when conditions were propitious for fighting. Additionally, trade, and gatherings associated therewith, was largely seasonally based. To stop the calendar months
(which are a little shorter than Julian calendar months) from rotating through the seasons, intercalation was employed. This involved the occasional insertion of an extra month (announced at the pilgrimage), ideally seven times in nineteen years. Intercalation was said to have been introduced in AD 412, and it was borrowed from the Jews. The Jewish official controlling the practice was known as Nasīʾ.
When the Arabs adopted the procedure they used this word nasīʾ to denote the whole system. It was operated similarly to the way the Jews operated it – the beginning of the year (Muharram) was tied to the spring season.
