حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى، عَنِ ابْنِ جُرَيْجٍ، عَنْ عَطَاءٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِذَا أَكَلَ أَحَدُكُمْ فَلاَ يَمْسَحَنَّ يَدَهُ بِالْمِنْدِيلِ حَتَّى يَلْعَقَهَا أَوْ يُلْعِقَهَا ‏"‏ ‏.‏

Ibn ‘Abbas reported the Messenger of Allah (PBUH) as saying : When one of you eats, he must not wipe his hand with a handkerchief till he licks it or gives it to someone to lick. Translation Not Available

Book Ref: Sunan Abi Dawud Book 28 Hadith 3847
Web Ref:  Sunan Abi Dawud Book 27 Hadith 3838