Hadith 140
حَدَّثَنَا هَارُونُ بْنُ إِسْحَاقَ الْهَمْدَانِيُّ قَالَ: حَدَّثَنَا عَبْدَةُ بْنُ سُلَيْمَانَ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنِ ابْنٍ لِكَعْبِ بْنِ مَالِكٍ، عَنْ أَبِيهِ قَالَ: «كَانَ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ يَأْكُلُ بِأَصَابِعِهِ الثَّلَاثِ وَيَلْعَقُهُنَّ»
It is narrated from Sayyiduna Ka'b bin Malik (may Allah be pleased with him), he says that the Messenger of Allah (peace and blessings be upon him) used to eat with three fingers and (after finishing the food) he would lick them.