Musnad Ahmad 435:57

Abu Abd al-Rahman said: Amr ibn Muhammad ibn Bukayr al-Naqid narrated to me, he said: Sufyan ibn Uyaynah narrated to us, from Hisham ibn Hujayr, from Tawus, from Ibn Abbas, who said: Muawiyah said to me: "Did you know that I shortened the hair of the Messenger of Allah, peace and blessings of Allah be upon him, with a pair of shears?" I said to him: "I do not know this to be anything but an argument against you."