Sahih al-Bukhari 1985
صحيح البخاري#1985SahihNarrated Abu Huraira:I heard the Prophet (ﷺ) saying, "None of you should fast on Friday unless he fasts a day before or after it
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: 30:92