Sahih al-Bukhari 6644
صحيح البخاري#6644SahihNarrated Anas bin Malik:I heard the Prophet (ﷺ) saying, "Perform the bowing and the prostration properly (with peace of mind), for, by Him in Whose Hand my soul is, I see you from behind my back when you bow and when you prostrate
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: 83:23