Sahih al-Bukhari 842
صحيح البخاري#842SahihNarrated Ibn `Abbas:I used to recognize the completion of the prayer of the Prophet (ﷺ) by hearing Takbir
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: 10:234