Which was the first prayer in Islam?

The first prayer to appear in Islam was the Dhuhr prayer. It was named as such because it was the first prayer that Jibreel (Gabriel) prayed with the Prophet, peace and blessings be upon him, after the prayer was enjoined on the night of Al-Isra (the Night Journey). It is stated in the Sahih (authentic collections of Hadith) that the Prophet, peace and blessings be upon him, used to pray Al-Hajeer, which you call Al-Ula (the first), when the sun passes its zenith. It is also mentioned in Al-Awsat, on the authority of Abu Hurairah and Abu Sa'id, that the first prayer enjoined was Dhuhr.