I heard the Messenger of Allah ﷺ say, "If a mutilated Ethiopian slave is appointed over you, listen to him and obey, so long as he leads you by the Book of Allah."
حدثنا أبو بكر بن أبي شيبة حدثنا وكيع بن الجراح عن شعبة عن يحيى بن الحصين عن جدته
سمعت رسول الله ﷺ يقول إن أمر عليكم عبد حبشي مجدع فاسمعوا له وأطيعوا ما قادكم بكتاب الله
Muslim narrated it in the Book of Leadership, Chapter on the Obligation to Obey Rulers Except in Sin, and the Prohibition of Obeying Them in Sin, hadith no. 1838, from Ibn Abu Shayba, through this same chain.