Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrated: The Messenger of Allah (peace and blessings be upon him) shaved his head during his Hajj, so some of the noble Companions (may Allah be pleased with them all) shaved their heads while others trimmed their hair. The Messenger of Allah (peace and blessings be upon him) said: "May Allah have mercy on those who shave their heads." They said: O Messenger of Allah! And those who trim their hair? He (peace and blessings be upon him) said: "May Allah have mercy on those who shave their heads." They said: O Messenger of Allah! And those who trim their hair? He (peace and blessings be upon him) said: "May Allah have mercy on those who shave their heads." They said: O Messenger of Allah! And those who trim their hair? He (peace and blessings be upon him) said: "And those who trim their hair." They said: O Messenger of Allah! What is the matter with those who shave their heads? Why did you express mercy for them? He (peace and blessings be upon him) said: "Because they did not show any doubt (and followed me by shaving their heads)."