Is it permissible to lick one's finger after eating out of forgetfulness of the fast, and is this considered issuing a fatwa without knowledge?

Speaking on matters of Sharia without knowledge is blameworthy. Licking fingers that have food on them is recommended by the majority of scholars, in order to maintain their cleanliness and to avoid arrogance. Licking is sought for fingers that have been soiled with food, and if one eats with three fingers, it is recommended to lick them. The word "his hand" in the hadiths may refer to the fingers or the entire palm.