The Prophet ﷺ said regarding the verse "Allah keeps firm those who believe with the firm word in worldly life and in the Hereafter" [Ibrahim 14:27], "It was revealed concerning the punishment of the grave. He is asked, 'Who is your Lord?' He replies, 'My Lord is Allah, and my religion is the religion of Muhammad ﷺ.' That is the meaning of His statement, 'Allah keeps firm those who believe with the firm word in worldly life and in the Hereafter' [Ibrahim 14:27]."
أخبرنا محمد بن بشار قال حدثنا محمد قال حدثنا شعبة عن علقمة بن مرثد عن سعد بن عبيدة
عن النبي ﷺ قال {يثبت الله الذين آمنوا بالقول الثابت في الحياة الدنيا وفي الآخرة} قال نزلت في عذاب القبر يقال له من ربك فيقول ربي الله وديني دين محمد ﷺ فذلك قوله {يثبت الله الذين آمنوا بالقول الثابت في الحياة الدنيا وفي الآخرة}
Recorded by Muslim, no. 2871 (see the previous hadith), from Muhammad bin Bashshar, and by Bukhari, in the Book of Funerals, chapter on what has been said regarding the punishment of the grave, no. 1369, from the hadith of Shubah with this wording, and from the hadith of Muhammad bin Bashshar as a suspended report, and it is also found in Al-Kubra, no. 2184.