Sayyiduna Abu Dharr (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) commanded me "to hear and obey, even if the ruler over me is an Abyssinian slave with mutilated limbs."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16768