Sahih al-Bukhari 858
صحيح البخاري#858SahihNarrated Abu Sa`id Al-Khudri:The Prophet (ﷺ) said, "Ghusl (taking a bath) on Friday is compulsory for every Muslim reaching the age of puberty
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: 10:249