Riyad as-Saliheen 750
Jabir (May Allah be pleased with him) reported:
Messenger of Allah ﷺ commanded the licking of fingers and the gleaning of the dish, saying, "You do not know in which portion the blessing lies."
[Muslim].
وعن جابر رضى الله عنه أن رسول الله ﷺ أمر بلعق الأصابع والصحفة، وقال:
"إنكم لا تدرون في أي طعامكم البركة" .
Classification
Sahih (Authentic)
References
Riyad as-Saliheen 750
Riyad as-Saliheen Book of Etiquette of Eating, Hadith 23