It is narrated from Umm Husayn (may Allah be pleased with her), the grandmother of Yahya bin Husayn, that:
I performed Hajj with the Messenger of Allah (peace and blessings be upon him) during the Farewell Pilgrimage, and he said many things. Then I heard him say: If a slave whose hands and feet are cut off, and who is black, is appointed as your leader, and he leads you according to the Book of Allah, then listen to him and obey him.