Musannaf Ibn Abi Shayba 33:1189

Ishaq bin Mansur narrated to us, he said: Abd al-Salam narrated to us, from Yazid bin Abd al-Rahman, from al-Minhal, from Khaythama, from Suwayd bin Ghafala, who said: When Allah wills to make the people of the Fire forget, He places for every person among them a coffin of fire according to his size, then He locks it upon him with locks of fire. No vein of his is struck except that there is a nail of fire in it. Then He places that coffin inside another coffin of fire, then He locks it with locks of fire, then He kindles a fire between them. So, none of them sees that there is anyone in the Fire other than himself. That is the saying of the Exalted: "They shall have coverings of fire from above them and coverings from beneath them." And that is His saying: "They shall have a bed of Hell, and from above them coverings. And thus do We recompense the wrongdoers."