Musnad Abu Ya'la al-Mawsili 45:4

Abu Bakr ibn Abi Shaybah narrated to us, Abdullah ibn Bakr al-Sahmi narrated to us, from Humayd, from Thabit, from Ishaq ibn Abdullah ibn Abi Talhah, from Abu Talhah: That the Prophet, peace and blessings of Allah be upon him, sacrificed two white-and-black rams. At the time of the first slaughter, he said: "On behalf of Muhammad and the family of Muhammad." And at the time of the second slaughter, he said: "On behalf of whoever believed in me and affirmed me from my nation."