Sahih al-Bukhari 562
صحيح البخاري#562SahihNarrated Ibn `Abbas:The Prophet (ﷺ) prayed seven rak`at together and eight rak`at together
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: 9:39