Muwatta Malik, Book 20, Hadith 798 (In-Book)

Yahya related to me from Malik from Nafi that Abdullah ibn Umar did not like people who were in ihram removing mites or ticks from their camels. Malik said, "This is what I like most out of what I have heard about the matter."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَكْرَهُ أَنْ يَنْزِعَ الْمُحْرِمُ، حَلَمَةً أَوْ قُرَادًا عَنْ بَعِيرِهِ ‏.‏ قَالَ مَالِكٌ وَذَلِكَ أَحَبُّ مَا سَمِعْتُ إِلَىَّ فِي ذَلِكَ ‏.‏

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also referenced under: Book 20, Hadith 96 (USC-MSA)