The Messenger of Allah ﷺ said, "No one should milk another person's livestock without his permission. Would any of you like someone to come to his storeroom, break open his pantry, and carry off his food? The udders of their livestock store their food for them, so no one should milk another's livestock except with his permission."
قال رسول الله ﷺ: لا يحلبن أحد ماشية امرئ بغير إذنه، أيحب أحدكم أن تؤتى مشربته، فتكسر خزانته، فينتقل طعامه؟ فإنما تخزن لهم ضروع مواشيهم أطعمتهم، فلا يحلبن أحد ماشية أحد إلا بإذنه.
Malik narrated it in "Seeking Permission" (17) from Nafi, from Ibn Umar, as mentioned.Bukhari narrated it in "Lost Property" (2435), and Muslim in "Lost Property" (1726), both from the hadith of Malik through the same chain, similarly.