Musnad Ahmad 26:251

Waki' narrated to us, Sufyan narrated to us, from his father, from Abu al-Duha, from Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, for every prophet there are allies among the prophets, and my ally among them is my father and the intimate friend of my Lord, Ibrahim." He said: Then he recited: "Indeed, the most worthy of Ibrahim are those who followed him" [Al-Imran: 68] to the end of the verse.