Muwatta Malik, Book 20, Hadith 93 (USC-MSA)

Yahya related to me from Yahya ibn Said from Muhammad ibn Ibrahim ibn alHarith at-Taymi from Rabia ibn Abi Abdullah ibn alHudayr that he saw Umar ibn al-Khattab taking the ticks off a camel of his at as- Suqya while he was in ihram. Malik said that he disapproved of that.

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ بْنِ الْحَارِثِ التَّيْمِيِّ، عَنْ رَبِيعَةَ بْنِ عَبْدِ اللَّهِ بْنِ الْهُدَيْرِ، أَنَّهُ رَأَى عُمَرَ بْنَ الْخَطَّابِ يُقَرِّدُ بَعِيرًا لَهُ فِي طِينٍ بِالسُّقْيَا وَهُوَ مُحْرِمٌ ‏.‏ قَالَ مَالِكٌ وَأَنَا أَكْرَهُهُ ‏.‏

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also referenced under: Book 20, Hadith 795 (In-Book)