Sunan Ibn Majah 3270
سنن ابن ماجه#3270Sahihحَدَّثَنَا مُوسَى بْنُ عَبْدِ الرَّحْمَنِ، أَنْبَأَنَا أَبُو دَاوُدَ الْحَفَرِيُّ، عَنْ سُفْيَانَ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " لاَ يَمْسَحْ أَحَدُكُمْ يَدَهُ حَتَّى يَلْعَقَهَا فَإِنَّهُ لاَ يَدْرِي فِي أَىِّ طَعَامِهِ الْبَرَكَةُ " .
It was narrated from Jabir that the Messenger of Allah (ﷺ) said:“None of you should wipe his hand until he has licked it, for he does not know where the blessing if in his food.’”
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 29:20