Muwatta Malik, Book 25, Hadith 5 (USC-MSA)

Yahya related to me from Malik from Nafi that Abdullah ibn Umar said about a trained dog, "Eat whatever it catches for you whether it eats from it or not."

وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ نَافِعٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ، أَنَّهُ كَانَ يَقُولُ فِي الْكَلْبِ الْمُعَلَّمِ كُلْ مَا أَمْسَكَ عَلَيْكَ إِنْ قَتَلَ وَإِنْ لَمْ يَقْتُلْ ‏.‏

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also referenced under: Book 25, Hadith 1058 (In-Book)