The Messenger of Allah ﷺ would lick his three fingers after eating. He said, "If a morsel of food falls from any of you, let him remove whatever has stuck to it and eat it, and not leave it for Satan."He also commanded us to wipe the bowl clean, saying, "For you do not know in which part of your food the blessing lies."
أن رسول الله ﷺ كان إذا أكل طعاما لعق أصابعه الثلاث، قال: وقال: إذا سقطت لقمة أحدكم فليمط عنها الأذى وليأكلها، ولا يدعها للشيطان وأمرنا أن نسلت القصعة قال: فإنكم لا تدرون في أي طعامكم البركة.
Muslim narrated it in the Book of Drinks (136:2034) through several routes from Bahz, who said, Hammad bin Salama narrated to us, who said, Thabit narrated to us, from Anas, who related it.