It wasnarrated from Jabir that the Messenger of Allah (ﷺ) said:
"Noneof you should wipe his hand until he has licked it, for he doesnotknow where the blessing if in his food.'" (RU)
English reference (RU): Vol. 4, Book 29, Hadith 3270 (RU)
Arabic reference (RU): Book 29, Hadith 3395 (RU)