Excellence of Eating with 5 Fingers & licking them, Islam is complete in all aspects and nothing can be added to its contents and nothing can be eliminated there from. Islam has put forward complete, comprehensive and eternal Shariah for us.
Messenger of Allah, Rasullah (s.a.) instructed His followers that after taking meal they should lick up their fingers before they wash or wipe them with a towel. Since Messenger of Allah ( s.a.) approved of this act, it is commendable.
To use less than 5 fingers for eating speaks of the manner of the arrogant, whereas to use both hands to this end is indicative of an overpowering greed. So, the best way of eating is that shown by Messenger of Allah ( s.a.). Here, too, is the affirmation of licking the fingers after taking meal, and not during it.
Present-day Muslims hardly care for this directive of Messenger of Allah (s.a.) because they think that this act will bring disgrace and dishonour upon them. To make matters worse, they throw away a large quantity of unconsumed food in street dumps, garbage bags and drains. They even deem it necessary to leave over some food in plates and dishes, still less of licking them. What a pity, the Muslim community has gone far away from the teachings and excellent example of their Rasul ( s.a.)!
Today, medical science says that, If a person eats with his fingers, and dips his fingers in the food while eating, some germs are made that allow to digest the food more easily, and the stomach doesn't get any problems. So you need to lick your fingers to lick the germs, which are good for your health. Licking fingers produces more saliva which helps to digest food faster.
This was told 1400 years by our Prophet(sa); today science has proved its beneficial values.