Musannaf Ibn Abi Shayba 8:2637

Abu Bakr narrated to us, he said: Abbad narrated to us, from Yahya bin Sa'id, from Muhammad bin Ibrahim, from Rabi'ah bin Abdullah bin al-Hudayr, who said: I saw Umar bin al-Khattab removing ticks from his camel at al-Suqya while he was in the state of ihram, and he was putting it into the mud.