Abu Huraira reported Allah's Messenger (ﷺ) as saying:When any one of you eats food he should lick his fingers, for he does not know in what part of the food sticking to his fingers the blessing lies.
وَحَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ، حَدَّثَنَا بَهْزٌ، حَدَّثَنَا وُهَيْبٌ، حَدَّثَنَا سُهَيْلٌ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِذَا أَكَلَ أَحَدُكُمْ فَلْيَلْعَقْ أَصَابِعَهُ فَإِنَّهُ لاَ يَدْرِي فِي أَيَّتِهِنَّ الْبَرَكَةُ " .
Muslim
The Book of Drinks • Hadith 181