Muwatta Malik, Book 24, Hadith 5 (USC-MSA)

Yahya related to me from Malik from Thawr ibn Zayd ad-Dili that Abdullah ibn Abbas was asked about animals slaughtered by the Christian Arabs. He said, "There is no harm in them," but he recited this ayat, "Whoever takes them as friends is from them." (Sura 5 ayat 54).

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ ثَوْرِ بْنِ زَيْدٍ الدِّيلِيِّ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّهُ سُئِلَ عَنْ ذَبَائِحِ، نَصَارَى الْعَرَبِ فَقَالَ لاَ بَأْسَ بِهَا وَتَلاَ هَذِهِ الآيَةَ ‏{‏وَمَنْ يَتَوَلَّهُمْ مِنْكُمْ فَإِنَّهُ مِنْهُمْ ‏}‏‏.‏

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also referenced under: Book 24, Hadith 1049 (In-Book)