Sunan Abi Dawud Book 28, Hadith 113
The Prophet (ﷺ) used to eat with three fingers and not wipe his before licking it.
When one of you eats, he must not wipe his hand with a handkerchief till he licks it or gives it to someone to lick.
When the food cloth was removed, the Messenger of Allah (ﷺ) said: “praise be to Allah abundantly and sincerely, of such a nature as is productive of blessing, is not insufficient, Abandoned, or ignored, O our lord.”