‏الحج : Hadeeth No:2983 'Abdullah reported that Allaah's Messenger (sallAllaahu alayhi wa sallam) got his head shaved (after slaughtering the sacrificial animal on the 10th of Dhu'l-Hijja), and so did a group of Companions, while some of them got their hair clipped. Abdullah said: Allaah's Messenger (may peace'be upon him)...

‏الإيمان : Hadeeth No:126 It is narrated on the authority of Abdullah b. Umar that the Prophet (may peace and blessings be upon him) observed on the occasion of the Farewell Pilgrimage Woe unto you distress unto you! Don't turn back as unbelievers after me by striking the necks of one another....