In his book entitled Al-Bidayah wan-Nihayah, Ibn Kathir cited the statements of the Muslim scholars regarding determining the night of the Prophet’s Ascension. These statements can be summarized in the following points:
The scholars of Seerah (the Prophet’s biography) differed regarding the exact year of the Prophet’s Night Journey and Ascension. It was said that it was about ten years after the beginning of the revelation, and this is the opinion of Ibn Ishaq. However, it is reported that Az-Zuhri and `Urwah maintain that the Prophet’s Night Journey (to Jerusalem) was one year before his Hijrah from Makkah to Madinah. On the other hand, Isma`il As-Saddi maintains that the Prophet’s Night Journey was sixteen months before his Hijrah to Madinah. Thus, according to the opinion of As-Saddi, the Prophet’s Night Journey was in the month of Dhul-Hijjah, and according to the opinion of Az-Zuhri and `Urwah, it was in the month of Rabi` Awwal. Moreover, Al-Hafiz `Abdul-Ghani ibn Surur Al-Maqdisi states that the Prophet’s Night Journey was on the night of Rajab 27. Yet some other scholars view that it was on the first Friday night of Rajab.
Sheikh Yusuf Al-Qaradawi states: In his book entitled Ada’ ma Wajaba fi Bayan Wad` Al-Wadda`ina fi Shahr Rajab, Abu Al-Khattab `Umar ibn Dahya, one of the scholars of the seventh Hijri century, states, “Some narrators maintained that the Night Journey of the Prophet (peace and blessings be upon him) was in Rajab, which is a mere lie.” This opinion of Abu Al-Khattab was confirmed by Al-Hafizh ibn Hajar Al-`Asqalani, the well-known exegete of Al-Bukhari’s authentic book of Hadith. Personally, I know that there is not any authentic hadith or a saying of a Companion stating that the Prophet’s Night Journey was on Rajab 27. Rather, it is just a circulating baseless opinion maintained by some early scholars. It was attributed to Imam An-Nawawi in some of his fatwas; since An-Nawawi was an eminent popular Muslim scholar, this opinion (that the Night Journey was on Rajab 27) spread at that time. However, Imam Abu Ishaq Al-Harbi, for example, stated that the Prophet’s Night Journey was not on Rajab 27, but it was on the night of Rabi` Awwal 27.
As far as I know, I am certain that the opinion relating the Prophet’s Night Journey to Rajab 27 is not authenticated; it is just a baseless widespread belief that has been popular among Muslims for centuries. Still, since such a belief has nothing to do with religious deeds and acts of worship, on Rajab 27, a Muslim is not required to perform special Night Vigil Prayer (Tahajjud), nor is he required to fast by day, nor is he enjoined to perform any special act of worship. The Muslims should not give any special importance to that day. They can hold a ceremony on this occasion if the purpose is just to study and contemplate such a great event and its effect on the life of the Prophet (peace and blessings be upon him). This is because it followed the Year of Sorrow (in which the Prophet’s wife and uncle died), so Allah wanted to relieve and honour His Messenger after he was rejected and severely hurt by the disbelievers of the Quraysh and Thaqif tribes. Thus, Allah honoured His Messenger after such suffering by taking him in a night journey to Jerusalem and making him lead all the prophets in Prayer there, then taking him in a journey of ascension to the high heavens where he was warmly received by the angels and the prophets. The lessons are the most important thing regarding this great event. So, as long as it does not affect one’s deeds or acts of worship, there is no harm in celebrating such an event to study it and benefit from its lessons.