Sahih al-Bukhari 4919
صحيح البخاري#4919SahihNarrated Abu Sa`id:I heard the Prophet (ﷺ) saying, "Our Lord Allah will lay bare His Shin, and then all the Believers, men and women, will prostrate themselves before Him, but there will remain those who used to prostrate in the world for showing off and for gaining good reputation. Such people will try to prostrate (on the Day of Judgment) but their back swill be as stiff as if it is one bone (a single vertebra)
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: 65:439