Musnad Ahmad 31:398

Surayj and ‘Affan narrated to us, they said: Hammad narrated to us, and ‘Affan said: Al-Hajjaj informed us, from ‘Atiyyah ibn Sa‘d, from Abu Sa‘id al-Khudri, that he said: I asked the Prophet (peace be upon him) — or a man asked him — and said: "O Messenger of Allah, a wolf bit off the tail of a sheep of mine, shall I offer it as a sacrifice?" He said: "Yes." And ‘Affan said: Regarding the tail of a sheep of his that the wolf bit off, he said: "Shall I offer it as a sacrifice?" He said: "Yes."