Musnad Ahmad 25:1273

Muhammad ibn Ja’far and Bahz narrated to us, they said: Shu’bah narrated to us, from Habib—Bahz said: Habib ibn Abi Thabit narrated to us—he said: I heard Sa’id ibn Jubayr narrating from Ibn Abbas, who said: "As-Sa’b—and Ibn Ja’far said: Ibn Juththamah—gifted to the Messenger of Allah, may Allah bless him and grant him peace, a piece of a wild donkey while he was in the state of ihram, so he returned it." Bahz said: "The hindquarters of a donkey, or he said: the leg of a donkey."