Mukhtasar Muslim

Narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings of Allah be upon him) said: None of you should milk the animal of another without his permission. Does any of you wish that someone should come into his storeroom, break open his treasure, and take away his food grain? Similarly, the udders of animals are their food treasures. So no one should milk the animal of another without his permission (except one who is dying of hunger, he may take as much as is necessary).