Ka‘b ibn Mālik (may Allah be pleased with him) reported: I saw the Messenger of Allah (may Allah's peace and blessings be upon him) eating with three fingers, and when he finished eating, he would lick them.
شرح الحديث :
The Prophet (may Allah's peace and blessings be upon him) used to eat with three fingers, and he wouldn't use his other fingers, except when necessary. And, when he had finished eating, he would lick his fingers.