Abu Ma'mar says that once we were present with Sayyiduna Ali (may Allah be pleased with him), a funeral passed by there, and people stood up upon seeing it. Sayyiduna Ali (may Allah be pleased with him) asked, "Who told you about this ruling?" The people mentioned the name of Sayyiduna Abu Musa Ash'ari (may Allah be pleased with him). Sayyiduna Ali (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) did this only once, and that too because the Prophet (peace and blessings be upon him) used to adopt the practices of the People of the Book, but when it was prohibited, he (peace and blessings be upon him) stopped.