Musnad Ahmad 435:59

'Abdullah said: Abu Bakr ibn Abi Shaybah narrated to us, Muhammad ibn 'Abdullah al-Asadi narrated to us, from Sufyan, from Ja'far, from his father, from Ibn 'Abbas, from Mu'awiyah, who said: I saw the Prophet, peace and blessings of Allah be upon him, shortening [his hair] with a *mishqas* (a pair of scissors or a blade).