It is narrated from Hazrat Anas (may Allah be pleased with him) that a funeral passed in front of the Prophet (peace and blessings be upon him). Someone praised the deceased, then several people praised him. The Prophet (peace and blessings be upon him) said, "It has become obligatory." Then another funeral passed and people criticized the deceased, and seeing them, many others also criticized him. The Prophet (peace and blessings be upon him) said, "It has become obligatory. You are Allah's witnesses on earth."