Musnad Ahmad 31:819

Hajjaj ibn Muhammad narrated to us, from Shu'bah, from Jabir, who said: I heard Muhammad ibn Qurazah narrating from Abu Sa'id al-Khudri, that he bought a ram to sacrifice it, and a wolf ate from its tail or its rump. So I came to the Prophet, peace and blessings of Allah be upon him, and asked him, and he said: "Sacrifice it."