Musnad Ahmad 25:22

Hashim narrated to us, Hushaym informed us, from Yazid ibn Abi Ziyad, from Miqsam, from Ibn Abbas, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "O Allah, forgive those who shave." A man said: "And those who shorten?" He said: "O Allah, forgive those who shave." The man said: "And those who shorten?" He said in the third—or the fourth—time: "And those who shorten."