Musnad Ahmad 5:289

Hassan ibn Musa narrated to us, Zuhayr narrated to us, Mansur ibn al-Mu'tamir narrated to us, from Abu Ishaq, from al-Harith, from Ali, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If I were to appoint anyone from my Ummah as a leader without consultation among them, I would have appointed Ibn Umm 'Abd over them."