Musannaf Ibn Abi Shayba 27:480

'Affan narrated to us, he said: Hammad bin Salamah narrated to us, he said: 'Ali bin Zayd informed us, from 'Adi bin Thabit, from al-Bara', who said: We were with the Messenger of Allah (may Allah bless him and grant him peace) on a journey. He said: So we descended at Ghadir Khumm. It was announced: "Prayer is congregational." The ground under a tree was swept for the Messenger of Allah (may Allah bless him and grant him peace), and he prayed the Dhuhr prayer. Then he took the hand of 'Ali and said: "Do you not know that I am closer to the believers than their own selves?" They said: "Yes." He said: "Do you not know that I am closer to every believer than his own self?" They said: "Yes." He said: So he took the hand of 'Ali and said: "O Allah, whoever I am his master (mawla), then 'Ali is his master. O Allah, befriend whoever befriends him, and be hostile to whoever is hostile to him." He said: Then 'Umar met him after that and said: "Congratulations to you, O son of Abu Talib! You have become, morning and evening, the master of every believing man and believing woman."