Musnad Abu Ya'la al-Mawsili 148:50

Muhammad ibn Bahr in Balhujaym in Basra narrated to us, 'Adi ibn Abi 'Amarah al-Jarmi narrated to me, Ziyad al-Numayri narrated to us, from Anas ibn Malik, who said: We were with the Messenger of Allah (peace and blessings of Allah be upon him), and he entered one of the houses of the Banu al-Najjar. He came out to us with his color changed, and he said: "Whose graves are these?" They said: "Graves of people who died in the Jahiliyyah (pre-Islamic era)." He then turned to us and said: "Seek refuge in Allah from the punishment of the grave. For by the One in whose hand is my soul, I have seen their bodies, how they are being punished in their graves."