It was narrated that 'Ali said:
"The Messenger of Allah said: 'If I were to appoint anyone as my successor without consulting anyone, I would have appointed Ibn Umm 'Abd.'" (RU)
English reference (RU): Vol. 1, Book 1, Hadith 137 (RU)
Arabic reference (RU): Book 1, Hadith 142 (RU)