Affan narrated that "Hammad ibn Salamah" narrated that "Ali bin Zaid" told us that "Adi ibn Thabit" said that Al Barra'a Ibn Aazib said that:
We were with the Messenger of Allah -peace be upon him- in a travel journey we were involved in, when we camped in 'Ghadeer Khumm'. The call for congregational prayers was made. A site between two trees was chosen, and was swept clean for the prophet peace be upon him. He performed the noon-time prayers then took `Ali by the hand and asked the crowd: `Do you not know that I have more authority over the believers than the believers have over themselves?' They answered: `Yes, we do.' He asked: `Do you know that I have more authority over every believer than the believer has over himself ?' They answered in the affirmative; then he took `Ali's hand and said: `Whoever has accepted me as his master, this `Ali is his master; O Lord! Befriend whoever befriends him and be the enemy of whoever chooses to be his enemy.' `Umer met him immediately following that and said to him: `Congratulations to you, son of Abu Talib! You have become, at dawn and at sunset, the master of every believing man and woman.'"
