Musannaf Ibn Abi Shayba 16:229

Abu Bakr narrated to us, he said: Abd al-Wahhab al-Thaqafi narrated to us, from Humayd, from Anas, that a morsel fell from his hand, so he searched for it until he found it. And he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "If a morsel of one of you falls, let him remove what is upon it, then let him eat it, and let him not leave it for the Shaytan."