Sahih Muslim

Al-Bara' b. `Azib reported Allah's Apostle (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