Sahih al-Bukhari 1146
صحيح البخاري#1146SahihNarrated Al-Aswad:I asked `Aisha "How is the night prayer of the Prophet?" She replied, "He used to sleep early at night, and get up in its last part to pray, and then return to his bed. When the Mu'adh-dhin pronounced the Adhan, he would get up. If he was in need of a bath he would take it; otherwise he would perform ablution and then go out (for the prayer)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 19:27