Sahih Ibn Khuzaymah

Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates that the Noble Prophet (peace be upon him) had his head shaved during the Farewell Pilgrimage. Ibn Jurayj says that people used to shave their heads at the time of Hajj, then when returning from Mina, they would perform Umrah and say, "Now what will he shave?" So we would say to each other, "Pass the razor over your head."