Sahih Muslim 1065
صحيح مسلم#1065SahihAl-Bara' reported:When we were (in prayer) with the Messenger of Allah Allah (ﷺ) none of us benfft his back till we saw he prostrated. Zuhair and others reported:" till we saw him prostrating
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 4:227