Section 1 Mishkat al-Masabih 4166
Arabic hadith text
وَعَنِ ابْنِ عَبَّاسٍ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «إِذَا أَكَلَ أَحَدُكُمْ فَلَا يمسحْ يدَه حَتَّى يلعقها أَو يلعقها»
Translation
Ibn ‘Abbas reported the Prophet as saying, “When one of you eats he must not wipe his hand till he licks it, or gives it to someone to lick.” (Bukhari and Muslim.)