Licking fingers of left hand if used in eating
9-5-2017 | IslamWeb
Question:
Assalaamu alaykum wa rahmatullaahi wa barakaatuhu Shaykh. Is it from the Sunnah to lick the fingers after a meal? If yes, then what if the fingers of the left hand were also used during the meal, is it from the Sunnah to lick them too, or not? As we know, food should not be eaten with the left hand, which is why I am asking this question, so what about the fingers of the left hand? I mean, for example when eating chicken or meat, they are also used. May Allaah reward you.
Answer:
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad 
is His slave and Messenger.
We have already issued fatwa 319630 clarifying that licking the fingers after eating is from the Sunnah.
As for licking the fingers of the left hand if it is used in eating and some food remained on it, then we did not come across any statement of the scholars about it. This is something that is probable, and it can be argued that this is permissible due to the existence of the reason mentioned in the Sunnah, which is the saying of the Prophet "If anyone of you eats, then let him lick his fingers, as he does not know in which finger the blessing is." Another hadeeth reads, "...as he does not know in which food the blessing is." [Muslim]
Ibn Daqeeq Al-‘Eed said in Ihkaam Al-Ahkaam, "The reason for this is mentioned in some narrations: 'He does not know in which food the blessing is.' ... If the hadeeth is proven to be authentic, then we act according to it." [Abridged]
Ibn Hajar 
said in Fat'h al-Baari:
"Iyaadh indicated another reason, as he said, 'Rather, he ordered this so that the people would not neglect eating the little food (that is left).' An-Nawawi said, 'The meaning of the phrase ‘in which food the blessing is’ is that the food that is presented to the person, there is blessing in it, and he does not know whether the blessing is in what he ate, in what remains on his fingers, in what remained at the bottom of the bowl, or in the fallen piece of food; so he should eat all of this in order to attain the blessing.'"
There is no doubt that the reason applies to the food that is left on the left hand; therefore, the ruling applies to it due to the existence of the reason. To illustrate this, if someone has his right hand amputated and he ate with his left hand, then this ruling is apparent in his case.
Accordingly, if someone is in need of holding some food with his left hand along with the right hand and there is some food left on his left hand, then it becomes permissible for him to lick the food from both hands.
Allah knows best.