Musnad Ahmad 31:16

Abu Amir narrated to us, Abbad—meaning Ibn Rashid—narrated to us, from Dawud ibn Abi Hind, from Abu Nadrah, from Abu Sa’id al-Khudri, who said: I witnessed a funeral with the Messenger of Allah, peace and blessings of Allah be upon him. The Messenger of Allah, peace and blessings of Allah be upon him, said: "O people, this nation is tested in its graves. When a person is buried and his companions depart from him, an angel comes to him with a hammer in his hand and makes him sit up. He says: 'What do you say about this man?' If he is a believer, he says: 'I bear witness that there is no god but Allah and that Muhammad is His servant and His Messenger.' He says: 'You have spoken the truth.' Then a door to the Fire is opened for him, and he says: 'This would have been your dwelling had you disbelieved in your Lord, but since you believed, this is your dwelling.' Then a door to Paradise is opened for him, and he wishes to rise toward it, but he says to him: 'Remain calm,' and his grave is expanded for him. If he is a disbeliever or a hypocrite, he says to him: 'What do you say about this man?' He says: 'I do not know; I heard the people saying something.' He says: 'You did not know, you did not recite, and you were not guided.' Then a door to Paradise is opened for him, and he says: 'This would have been your dwelling had you believed in your Lord, but since you disbelieved in Him, Allah the Almighty has replaced it for you with this.' Then a door to the Fire is opened for him, and he strikes him a blow with the hammer that everything Allah has created hears, except for the two heavy ones (jinn and mankind)." Some of the people said: "O Messenger of Allah, there is no one over whom an angel stands with a hammer in his hand but that he would be terrified at that." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Allah keeps firm those who believe with the firm word" [Ibrahim: 27].