«إذا أتى أحدكم على ماشية فإن كان فيها صاحبها فليستأذن فإن أذن له فليحتلب وليشرب, وإن لم يكن فيها فليصوت ثلاثا فإن أجابه أحد فليستأذنه فإن لم يجبه أحد فليحتلب وليشرب ولا يحمل»
The Prophet (peace and blessings be upon him) said:
"When any of you comes to a herd of livestock, if their owner is present there, he should ask his permission; if he gives him permission, he may milk and drink. And if no one is present there, he should call out three times; then if anyone answers, he should ask his permission, and if no one answers, he may milk and drink, but he should not carry any away with him."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 265