Musnad Abu Ya'la al-Mawsili 110:150

From Hushaem, from Yazid ibn Abi Ziyad, from Miqsam, from Ibn Abbas, that the Messenger of Allah (may Allah bless him and grant him peace) said: "O Allah, forgive those who shave." A man said: "And those who shorten?" He said: "O Allah, forgive those who shave." He said in the third or fourth [time]: "And those who shorten."