Musnad Ahmad 27:640

Isma'il narrated to us, Yahya ibn Abi Ishaq narrated to us, a man from Banu Ghifar narrated to me in the gathering of Salim ibn 'Abdullah: So-and-so narrated to me that the Messenger of Allah (peace and blessings of Allah be upon him) was brought food consisting of bread and meat. He said: "Hand me the forearm." So a forearm was handed to him, and he ate it. Yahya said: I do not know it except as such. Then he said: "Hand me the forearm." So a forearm was handed to him, and he ate it. Then he said: "Hand me the forearm." He said: "O Messenger of Allah, there are only two forearms." He said: "By your father, had you remained silent, I would have continued to be handed a forearm as long as I called for it." Salim said: As for this, I did not hear it. I heard 'Abdullah ibn 'Umar say: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah, Blessed and Exalted is He, forbids you from swearing by your fathers."