Sunan Ibn Majah, Book 29, Hadith 3393 (In-Book) ⓘ
It was narrated from Ibn ‘Abbas that the Prophet said: “When one of you eats food, let him not wipe his hand until he has licked it or has someone else to lick it.”
حَدَّثَنَا مُحَمَّدُ بْنُ أَبِي عُمَرَ الْعَدَنِيُّ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ عَطَاءٍ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ قَالَ " إِذَا أَكَلَ أَحَدُكُمْ طَعَامًا فَلاَ يَمْسَحْ يَدَهُ حَتَّى يَلْعَقَهَا أَوْ يُلْعِقَهَا " .
also referenced under: Hadith 3269 (Reference) & Volume 4, Book 29, Hadith 3269 (DarusSalam)