Narrated Al-Bara' bin 'Azib :
The Prophet (p.b.u.h) 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."
Narrated Al-Bara bin Azib:
Allah's Messenger (ﷺ) said, "When a Muslim is questioned in his grave, he will testify that none has the right to be worshipped but Allah and that Muhammad is Allah's Messenger, and that is what is meant by Allah's Statement:-- "Allah will keep firm those who believe with a Word that stands firm in this world and in the Hereafter." (14.27)
Al-Bara' b. `Azib reported Allah's Messenger (ﷺ) as saying: This verse: "Allah grants steadfastness to those who believe with firm word," was revealed in connection with the torment of the grave. It would be said to him: Who is your Lord? And he would say: Allah is my Lord and Muhammad is my Apostle (ﷺ), and that is (what is implied) by the words of Allah, the Exalted: "Allah keeps steadfast those who believe with firm word in this world and in the Hereafter."
Al-Bara' b. 'Azib reported that this verse: "Allah keeps those who believe steadfast with firm word in this world and the Hereafter" was revealed in connection with the torment of the grave.