It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "O Allah! Forgive those who shave their heads." The people said: "And for those who shorten their hair, O Messenger of Allah." The Prophet (peace and blessings be upon him) then, on the third or fourth time, said for those who shorten their hair: "O Allah! Forgive those who shorten their hair as well."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4897