Abdullah bin Ka'b or Abdur Rahman bin Ka'b (Hisham bin Urwah was unsure) reported, their father Sayyiduna Ka'b bin Malik (may Allah be pleased with him) narrated that the Noble Prophet (peace and blessings be upon him) used to eat with three fingers, and when he finished eating, he would lick them. Hisham bin Urwah indicated towards the three fingers to explain.
Hadith Referenceسنن دارمي / من كتاب الاطعمة / 2073
Hadith Takhrijاس روایت کی سند جید ہے اور عبدالله و عبدالرحمٰن دونوں سیدنا کعب بن مالک رضی اللہ عنہ کے بیٹے ہیں جو ثقات التابعين میں سے ہیں، اس حدیث کا حوالہ اوپر گذر چکا ہے۔
Brief Explanation
(Commentary on Hadiths 2071 to 2073) From these hadiths, eating with three fingers, licking them, and then cleaning or washing them is established. Those people who consider licking fingers to be against etiquette are deprived of the blessing of following the Sunnah, the value and worth of sustenance, and gratitude to Allah. May Allah grant them insight and bestow upon them the ability to follow the Sunnah, ameen.