Sahih al-Bukhari 1369
صحيح البخاري#1369SahihNarrated Al-Bara' bin 'Azib : The Prophet (ﷺ) said, "When a faithful believer is made to sit in his grave, then (the angels) come to him and he testifies that none has the right to be worshipped but Allah and Muhammad is Allah's Apostle. And that corresponds to Allah's statement: Allah will keep firm those who believe with the word that stands firm . . . (14.27). Narrated Shu'ba: Same as above and added, "Allah will keep firm those who believe . . . (14.27) was revealed concerning the punishment of the grave
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: 23:121