The Book About the Etiquette of Eating
Riyad as-Salihin #69
كتـــــاب أدب الطعام
وعن كعب بن مالك رضى الله عنه قال: رأيت رسول الله صلى الله عليه وسلم يأكل بثلاث أصابع، فإذا فرغ لعقها.((رواه مسلم))
Ka'b bin Malik (May Allah be pleased with him) reported:
I saw Messenger of Allah (ﷺ) eating with three fingers (i.e., the thumb, the index finger and the middle finger) and licking them after having finished the food..
وعن كعب بن مالك رضى الله عنه قال: رأيت رسول الله صلى الله عليه وسلم يأكل بثلاث أصابع ، فإذا فرغ لعقها.((رواه مسلم))
I saw Messenger of Allah (ﷺ) eating with three fingers (i.e., the thumb, the index finger and the middle finger) and licking them after having finished the food..
— Riyad as-Salihin, Hadith 69