“Abu ‘Abd Allah, ‘Alayhi al-Salam, has stated this Hadith. ‘The Messenger of Allah (sawa) has said, “When one of you eats food he should wipe (lick) his fingers, clean with which he has eaten; Allah, most Majestic, most Glorious, says, ‘Allah grants you blessings.’”’”
Sanad: Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Qasim ibn Yahya from his grandfather al-Hassan ibn Rashid from abu Basir who has said the above hadith
Source: al-Kafi, Volume 6, Chapter , Hadith #7 (See Image below)
Grading: al-Mohsini grades it a reliable hadith [Mu`jim al-Ahhadith al-Mu`tabara, Volume 7, page 467]
One should lick one’s fingers clean after taking food.