Riyad as-Salihin 748
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. [Muslim] .
وعن كعب بن مالك رضى الله عنه قال‏:‏ رأيت رسول الله صلى الله عليه وسلم يأكل بثلاث أصابع ، فإذا فرغ لعقها‏.‏‏‏((رواه مسلم))‏
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