Musannaf Ibn Abi Shayba 16:218

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah narrated to us, from ‘Amr, from ‘Ata’, from Ibn ‘Abbas, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "When one of you eats his food, let him not wipe his hand until he licks it or has it licked."