Hazrat Abdullah bin Umar (may Allah be pleased with them both) narrated that the Messenger of Allah (peace and blessings be upon him) said: No person should milk someone else's milch animal without the owner's permission. Would anyone like that a stranger enters his storeroom, opens his storage, and steals his grain from there? The udders of people's cattle are also their food storage (i.e., milk stores) for them. Therefore, they should not be milked without the owner's permission.