The Book of Drinks
36/18. Chapter:
It is recommended to lick one's fingers and wipe the bowl, and to eat a piece of food that is dropped after removing any dirt on it. It is disliked to wipe one's hand before licking it, because of the possibility that the blessing of the food may be in that remaining part. The Sunnah is to eat with three fingers
Sahih Muslim
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَزُهَيْرُ بْنُ حَرْبٍ، وَمُحَمَّدُ بْنُ حَاتِمٍ، قَالُوا حَدَّثَنَا ابْنُ، مَهْدِيٍّ عَنْ سُفْيَانَ، عَنْ سَعْدِ بْنِ إِبْرَاهِيمَ، عَنِ ابْنِ كَعْبِ بْنِ مَالِكٍ، عَنْ أَبِيهِ، قَالَ رَأَيْتُ النَّبِيَّ صلى الله عليه وسلم يَلْعَقُ أَصَابِعَهُ الثَّلاَثَ مِنَ الطَّعَامِ . وَلَمْ يَذْكُرِ ابْنُ حَاتِمٍ الثَّلاَثَ . وَقَالَ ابْنُ أَبِي شَيْبَةَ فِي رِوَايَتِهِ عَنْ عَبْدِ الرَّحْمَنِ بْنِ كَعْبٍ عَنْ أَبِيهِ .
Ibn Ka'b b. Malik reported on the authority of his father that he saw Allah's Messenger (ﷺ) licking his three fingers (after having finished the food). Ibn Hatim made no mention of" three". This hadith is also narrated through another chain of transmitters.
Reference : Sahih Muslim 2032aIn-book reference : Book 36, Hadith 170USC-MSA web (English) reference : Book 23, Hadith 5039