Musannaf Ibn Abi Shayba 13:2340

Abu Bakr narrated to us, he said: Abu Usamah narrated to us, he said: Ubaydullah ibn Umar narrated to us, from Nafi’, from Ibn Umar, he said: The Messenger of Allah (may Allah bless him and grant him peace) forbade that livestock be milked except with the permission of their owners. And he said: "Would any of you like for his storehouse, in which his food is, to be approached, its door broken, and what is inside it to be taken? For indeed, what is in the udders of their livestock is like what is in your storehouses. Beware, it is not lawful that what is in their udders be taken except with the permission of their owners."