Sahih al-Bukhari 1139
صحيح البخاري#1139SahihNarrated Masruq:I asked Aisha about the night prayer of Allah's Messenger (ﷺ) and she said, "It was seven, nine or eleven rak`at besides the two rak`at of the Fajr prayer (i.e. Sunna)
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: 19:20