Musannaf Ibn Abi Shayba 19:565

Abu Bakr narrated to us, he said: Abd al-Wahhab al-Thaqafi narrated to us, from Ayyub, from Abu Qilabah, from Ibn Abbas, that he was asked about shaving [the head]. He said: "Allah made it a rite and a Sunnah, and the people made it a punishment."