Narrated Samurah ibn Jundub: The Prophet (ﷺ) said: When one of you comes to the cattle, he should seek permission of their master if he is there; if he permits, he should milk (the animals) and drink. If he is not there, he should call three times. If he responds, he should seek his permission; otherwise, he may milk (the animals) and drink, but should not carry (with him).
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا عَيَّاشُ بْنُ الْوَلِيدِ الرَّقَّامُ، حَدَّثَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، عَنِ الْحَسَنِ، عَنْ سَمُرَةَ بْنِ جُنْدُبٍ، أَنَّ نَبِيَّ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا أَتَى أَحَدُكُمْ عَلَى مَاشِيَةٍ فَإِنْ كَانَ فِيهَا صَاحِبُهَا فَلْيَسْتَأْذِنْهُ فَإِنْ أَذِنَ لَهُ فَلْيَحْلِبْ وَلْيَشْرَبْ فَإِنْ لَمْ يَكُنْ فِيهَا فَلْيُصَوِّتْ ثَلاَثًا فَإِنْ أَجَابَهُ فَلْيَسْتَأْذِنْهُ وَإِلاَّ فَلْيَحْتَلِبْ وَلْيَشْرَبْ وَلاَ يَحْمِلْ " .
sunnah.com