It was narrated from 'Abdullah bin 'Umar that the Messenger of Allah (ﷺ) stood up and said: "No one of you should milk from the livestock of another man without his permission. Would anyone of you like someone to break into his storeroom and take his food? The udders of their livestock store food for them, so none of you should milk the livestock of another man without his permission."
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، قَالَ أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنْ رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ أَنَّهُ قَامَ فَقَالَ " لاَ يَحْتَلِبَنَّ أَحَدُكُمْ مَاشِيَةَ رَجُلٍ بِغَيْرِ إِذْنِهِ أَيُحِبُّ أَحَدُكُمْ أَنْ تُؤْتَى مَشْرُبَتُهُ فَيُكْسَرَ بَابُ خِزَانَتِهِ فَيُنْتَثَلَ طَعَامُهُ فَإِنَّمَا تَخْزُنُ لَهُمْ ضُرُوعُ مَوَاشِيهِمْ أَطْعِمَاتِهِمْ فَلاَ يَحْتَلِبَنَّ أَحَدُكُمْ مَاشِيَةَ امْرِئٍ بِغَيْرِ إِذْنِهِ " .
sunnah.com