Maliks Muwatta Book 20, Hadith Number 50.

Section : How the People of Makka, and Those Besides Them Living There, Go into Ihram.

Yahya related to me from Malik, from Abd ar-Rahman ibn al-Qasim, from his father, that Umar ibn al-Khattab said, “People of Makka, why is it that people arrive dishevelled while you still have oil on your hair? Go into ihram when you see the new moon.”