Musannaf Ibn Abi Shayba 35:98

Waki’ narrated to us, from Usama bin Zayd, from ‘Ata’, from Jabir, who said: A man said, "O Messenger of Allah (may Allah bless him and grant him peace), I shaved before I slaughtered." He said, "There is no harm." And he mentioned that Abu Hanifa said, "He owes a blood sacrifice (dam)."