حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ عَلْقَمَةَ بْنِ مَرْثَدٍ، عَنْ سَعْدِ بْنِ عُبَيْدَةَ، عَنِ الْبَرَاءِ بْنِ عَازِبٍ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَ ‏:‏ ‏"‏ ‏{يُثَبِّتُ اللَّهُ الَّذِينَ آمَنُوا بِالْقَوْلِ الثَّابِتِ }‏ قَالَ ‏:‏ نَزَلَتْ فِي عَذَابِ الْقَبْرِ يُقَالُ لَهُ ‏:‏ مَنْ رَبُّكَ فَيَقُولُ ‏:‏ رَبِّيَ اللَّهُ وَنَبِيِّي مُحَمَّدٌ فَذَلِكَ قَوْلُهُ ‏{يُثَبِّتُ اللَّهُ الَّذِينَ آمَنُوا بِالْقَوْلِ الثَّابِتِ فِي الْحَيَاةِ الدُّنْيَا وَفِي الآخِرَةِ}‏ ‏"‏ ‏.‏

It wasnarrated from Bara’ bin ‘Azib that the Prophet (PBUH) said: “Allahwill keep firm those who believe, with the word that standsfirm.”[14:27] This has been revealed concerning the torment of thegrave.It will be said to him: ‘Who is your Lord?’ He will say: ‘MyLord is Allah, and my Prophet is Muhammad.’ This is what Allahsays:Allah will keep firm those who believe, with the word thatstands firmin this world (i.e. they will keep on worshipping AllahAlone and noneelse), and in the Hereafter (i.e., at the time ofquestioning in thegrave).’” [14:27] Translation Not Available

Book Ref: Sunan Ibn Majah Book 37 Hadith 4269
Web Ref:  Sunan Ibn Majah Vol 5 Book 37 Hadith 4269