None (of you) should milk the animal of another, but with his permission. Does any one of you like that his chamber be raided, and his vaults be broken, and his foodstuff be removed? Verily the treasures for them (those who keep animals) are the udders of the animals which feed them. So none of you should milk the animal of another but with his permission.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لاَ يَحْلُبَنَّ أَحَدٌ مَاشِيَةَ أَحَدٍ إِلاَّ بِإِذْنِهِ أَيُحِبُّ أَحَدُكُمْ أَنْ تُؤْتَى مَشْرُبَتُهُ فَتُكْسَرَ خِزَانَتُهُ فَيُنْتَقَلَ طَعَامُهُ إِنَّمَا تَخْزُنُ لَهُمْ ضُرُوعُ مَوَاشِيهِمْ أَطْعِمَتَهُمْ فَلاَ يَحْلُبَنَّ أَحَدٌ مَاشِيَةَ أَحَدٍ إِلاَّ بِإِذْنِهِ  

This hadith has been narrated through another chain of transmitters with a slight variation of words.  

عَنِ النَّبِيِّ ﷺ نَحْوَ حَدِيثِ مَالِكٍ غَيْرَ أَنَّ فِي حَدِيثِهِمْ جَمِيعًا فَيُنْتَثَلَ إِلاَّ اللَّيْثَ بْنَ سَعْدٍ فَإِنَّ فِي حَدِيثِهِ فَيُنْتَقَلَ طَعَامُهُ كَرِوَايَةِ مَالِكٍ