It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "O Allah, forgive those who shave their heads." The Companions said: And those who trim their hair too? Then he (peace and blessings be upon him) said the third time: "And those who trim their hair too."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11104