Abu al-Tayyah says: I heard Anas (may Allah be pleased with him) say that the Messenger of Allah (peace and blessings be upon him) said to Abu Dharr (may Allah be pleased with him): "Listen and obey, even if it is an Abyssinian whose head is like a raisin."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5118