Hazrat Iyas bin Salamah narrates from his father that a funeral of a person from among the Ansar passed by the Prophet Muhammad (peace and blessings be upon him), and his virtues were mentioned. The Prophet (peace and blessings be upon him) said, "It has become obligatory." Then another funeral passed by, and his faults were mentioned. The Prophet (peace and blessings be upon him) said, "It has become obligatory." The companions asked, "O Messenger of Allah! What has become obligatory?" The Prophet (peace and blessings be upon him) said, "The angels are Allah's witnesses in the heavens, and you are Allah's witnesses on the earth."