Sahih al-Bukhari 836
صحيح البخاري#836SahihNarrated Abu Sa`id Al-Khudri:I saw Allah's Messenger (ﷺ) prostrating in mud and water and saw the mark of mud on his forehead
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: 10:229