'Abdullah b. Ka'b reported that his father Ka'b narrated to him that Messenger of Allah ﷺ used to eat with three fingers and when he had finished (eating), he licked them. (Using translation from Muslim 2032c)
أَنَّ رَسُولَ اللهِ ﷺ كَانَ يَأْكُلُ بِثَلَاثِ أَصَابِعَ فَإِذَا فَرَغَ لَعِقَهَا