'Abdullah b. Ka'b reported that his father Ka'b narrated to him that Allah's Messenger (ﷺ) used to eat with three fingers and when he had finished (eating), he licked them.
Sahih Muslim Book 36, Hadith 172
← Previous Hadith Ibn Ka'b b. Malik reported on the authority of his father that the Messenger of Allah (ﷺ) used to eat (food) with three fingers and he licked his hand before wiping it (with towel).

Sahih Muslim Book 36, Hadith 171 Next Hadith → A hadith like this has been reported on the authority of Ka'b b. Malik through another chain of transmitters.

Sahih Muslim Book 36, Hadith 173