Musnad Ahmad

Abu Al-Aswad (may Allah have mercy on him) says that once I set out towards Madinah Munawwarah. When I arrived there, I found out that a disease had spread there due to which people were dying in large numbers. I was sitting in the gathering of Sayyiduna Umar (may Allah be pleased with him) when a funeral passed by. The people praised the deceased, and Sayyiduna Umar (may Allah be pleased with him) said: "It has become obligatory." Then a second funeral passed by, and the people praised that deceased as well. Sayyiduna Umar (may Allah be pleased with him) again said: "It has become obligatory." A third funeral passed by, and the people spoke ill of that deceased. Sayyiduna Umar (may Allah be pleased with him) again said: "It has become obligatory." Eventually, I asked: "O Leader of the Believers! What has become obligatory?" He replied: "I only said what the Prophet (peace and blessings be upon him) said, that if four people testify to the goodness of a Muslim, Paradise becomes obligatory for him." We asked: "What if there are three people?" The Prophet (peace and blessings be upon him) said: "The same ruling applies." We asked about two people, and he (peace and blessings be upon him) said: "Even if there are two, the same ruling applies." Then we ourselves did not ask about one person.