Sahih Muslim
The Book of Pilgrimage (Kitab Al-Hajj)
Book Number: 007 / Hadith Number: 3003
Ibn Abbas (Allah be pleased with them) reported that it was said to Allah's Apostle (may peace be upon him) about sacrificing of animals, shaving of one's head, throwing of pebbles, and (the order of) precedence and succession, and he said: There is no harm in it.