Narrated Abu Sarihah, or Zaid bin Arqam - Shu'bah had doubt:
from the Prophet (ﷺ): "For whomever I am his Mawla then 'Ali is his Mawla." (JA)
English reference (JA): Vol. 1, Book 46, Hadith 3713 (JA)
Arabic reference (JA): Book 49, Hadith 4078 (JA)