Sayyiduna Ibn Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "May Allah have mercy on those who shave their heads." The people said: "O Messenger of Allah, and those who shorten their hair?" After three times he said: "And those who shorten their hair as well."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11444