Sunan Abi Dawud Book 28, Hadith 112
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.
If the servant of any of you prepares food for him, and he brings it to him, while he had suffered its heat and smoke. He should make him sit with him to eat. If the food is scanty, he should put one or two morsels in his hand.
The Prophet (ﷺ) used to eat with three fingers and not wipe his before licking it.