Sahih al-Bukhari 1981
صحيح البخاري#1981SahihNarrated Abu Huraira:My friend (the Prophet (ﷺ) ) advised me to observe three things: (1) to fast three days a month; (2) to pray two rak`at of Duha prayer (forenoon prayer); and (3) to pray witr before sleeping
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: 30:88