Musnad Ahmad 2:236

'Abd al-Samad and 'Affan narrated to us, they said: Dawud ibn Abi al-Furat narrated to us, 'Abdullah ibn Buraydah narrated to us—'Affan said: from Ibn Buraydah—from Abu al-Aswad al-Du'ali, he said: I came to Medina, and a disease had broken out in it—'Abd al-Samad said: and they were dying a rapid death—so I sat with 'Umar ibn al-Khattab. A funeral passed by him, and the deceased was praised with good, so he said: "It has become incumbent." Then another passed by, and the deceased was praised with good, so he said: "It has become incumbent." Then another passed by, and the deceased was praised with evil, so 'Umar said: "It has become incumbent." Abu al-Aswad said: I said to him: "O Commander of the Faithful, what has become incumbent?" He said: "I said as the Messenger of Allah (peace and blessings of Allah be upon him) said: 'Any Muslim for whom four bear witness to his goodness, Allah will cause him to enter Paradise.'" We said: "And three?" He said: "And three." We said: "And two?" He said: "And two." He said: And we did not ask him about one.