(52) باب لَعْقِ الأَصَابِعِ وَمَصِّهَا قَبْلَ أَنْ تُمْسَحَ بِالْمِنْدِيلِ
Narrated Ibn `Abbas:
The Prophet (ﷺ) said, 'When you eat, do not wipe your hands till you have licked it, or had it licked by somebody else."
Reference: Sahih al-Bukhari 5456
In-book reference: Book 70, Hadith 85
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 65, Hadith 366