Musnad Ahmad 25:1558

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Habib, from Sa'id ibn Jubayr, from Ibn Abbas, who said: As-Sa'b ibn Juthama gifted a wild donkey to the Messenger of Allah, may Allah bless him and grant him peace, while he was in a state of ihram. He returned it and said: "Were we not in a state of ihram, we would have accepted it from you."