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.’”
حَدَّثَنَا 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 " .
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Chapters on Food • Hadith 3270