All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The night of Al-Israa’ (the Night Journey of the Prophet, , to Jerusalem) and Al-Mi‘raaj (the Ascension) was among the signs proving the greatness of the Creator, and it proves the high status that the Prophet, , has in the sight of Allaah The Almighty as he ascended to the heavens and Allaah The Almighty spoke to him.
However, there is no authentic narration which proves which night it was. Even if we presume that there is such a narration, it is not permissible for the Muslims to single out the night of Al-Israa’ and Al-Mi’raaj with any special act of worship or celebration. This is because it is not reported from the Prophet, , or his Companions . If celebrating this night was permissible, the Prophet, , would have clarified this to his nation either by action or speech. Since no such thing was done by the Prophet, sallallaahu ‘alayhi wa sallam, or his Companions then we know that celebrating such a night has nothing to do with Islam but it is an innovation.
Indeed, the Prophet, sallallaahu ‘alayhi wa sallam, warned us against innovations as he said: "Whoever introduces into this matter of ours [Islam] that which is not a part of it, it will be rejected." [Al-Bukhari and Muslim] The Prophet, , also said: "Whoever introduces an act that is not in accordance with ours (concerning religion), it will be rejected." [Al-Bukhari and Muslim] Therefore, it becomes evident that the night of Al-Israa’ and Al-Mi’raaj is not specifically known and celebrating it is an evil innovation.
Allaah Knows best.