Sahih al-Bukhari 1123
صحيح البخاري#1123SahihNarrated `Aisha:Allah's Messenger (ﷺ) used to offer eleven rak`at and that was his prayer. He used to prolong the prostration to such an extent that one could recite fifty verses (of the Qur'an) before he would lift his head. He used to pray two rak`at (Sunna) before the Fajr prayer and then used to lie down on his right side till the call-maker came and informed him about 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: 19:3