Sahih Muslim | Book 23 | Hadith Number 5050

Narrated by Abu Huraira
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: When any one of you cats food he should lick his fingers, for hen does not know in what part of the food sticking to his fingers the blessing lies. This hadith has been reported on the authority of Hammad with the same chain of transmitters, but with a slight variation of wording.