Maliks Muwatta Book 20, Hadith Number 6.

Section : The Ghusl of Someone in Ihram.

Malik related to me from Nafi that Abdullah ibn Umar would spend the night between the two trails in the valley of Dhu Tuwa when he was approaching Makka. Then he would pray subh, and after that he would enter Makka by the trail which is at the highest part of Makka. He would never enter Makka, if he was coming for hajj or umra, without doing ghusl beforehand when he was near Makka at Dhu Tuwa, and he would tell whoever was with him to do likewise.