It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) appointed Hazrat Ibn Umm Maktum (may Allah be pleased with him) as his deputy in Madinah Munawwarah twice, and I saw Hazrat Ibn Umm Maktum holding a black flag on the day of the Battle of Qadisiyyah.