Maliks Muwatta Book 20, Hadith Number 93.
Section : Things that Someone in Ihram is Allowed to do.
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.