Sahih al-Bukhari 669
صحيح البخاري#669SahihNarrated Abu Sa`id Al-Khudri:A cloud came and it rained till the roof started leaking and in those days the roof used to be of the branches of date-palms. Iqama was pronounced and I saw Allah's Messenger (ﷺ) prostrating in water and mud and even I 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: 10:63