Sahih al-Bukhari 4569
صحيح البخاري#4569SahihNarrated Ibn `Abbas:I stayed overnight in the house of my aunt Maimuna. Allah's Messenger (ﷺ) talked with his wife for a while and then went to bed. When it was the last third of the night, he got up and looked towards the sky and said: "Verily! In the creation of the Heavens and the Earth and in the alteration of night and day, there are indeed signs for men of understanding." (3.190) Then he stood up, performed ablution, brushed his teeth with a Siwak, and then prayed eleven rak`at. Then Bilal pronounced the Adhan (i.e. call for the Fajr prayer). The Prophet (ﷺ) then offered two rak`at (Sunna) prayer and went out (to the Mosque) and offered the (compulsory congregational) Fajr 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: 65:91