Sahih al-Bukhari 798
صحيح البخاري#798SahihNarrated Anas:The qunut [supplication before going down for prostration] used to be recited in the Maghrib and the Fajr prayers
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: 10:193