Musannaf Ibn Abi Shayba 13:3280

Abu Bakr narrated to us, he said: Abu al-Ahwas narrated to us, from Zayd ibn Jubayr, he said: I was sitting with Ibn Umar when a man came to him and said: "A stray animal that I found." He said: "Make it sound (i.e., take care of it) and announce it." He said: "Is there any [sin] upon me if I drink from its milk?" Ibn Umar said: "I do not see any [sin] upon you in that."