Sahih Muslim Book 7, Hadith Number 2987.

Chapter : It is preferable to get one’s hair cut (as a ritual of pilgrimage) but clipping is also permissible.

Abu Huraira reported Allah’s Messenger (may peace be upon him) as having said: O Allah, grant pardon to those who got their heads shaved They (Companions of the Holy Prophet) said: Messenger of Allah, (what about those) who get their hair cut? He said: O Allah, grant pardon to those who get their heads shaved. They said: Messenger of Allah, (what about those) who got their hair clipped? He said: O Allah, grant pardon to those who get their heads shaved. They said: Messenger of Allah, (what about those) who get their hair clipped? He said: O Allah, grant pardon to those who get their heads shaved. They said: (What about those) who get their hair clipped? He said: (O Allah, grant pardon to) those who get their hair clipped.