عن ابن عباس رضى الله عنهما
قال: قال رسول الله صلى الله عليه وسلم: «إذا أكل أحدكم طعاماً، فلا يمسح أصابعه حتى يلعقها أو يلعقها»
Messenger of Allah (sallallahu alayhi wa sallam) said, “When one of you finishes eating, he should not wipe his fingers until he has licked them himself or has given them to someone else to lick for him.”.
Riyad as-Salihin 747, Book 3, The Book About the Etiquette of Eating, Hadith 21. 1 min read