Sahih al-Bukhari, Book 65, Hadith 4927 (In-Book)

Narrated Ibn `Abbas: The Prophet used to move his tongue when the divine Inspiration was being revealed to him. (Sufyan, a subnarrator, demonstrated (how the Prophet used to move his lips) and added. "In order to memorize it." So Allah revealed: "Move not your tongue concerning (the Qur'an) to make haste therewith." (75.16)

حَدَّثَنَا الْحُمَيْدِيُّ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا مُوسَى بْنُ أَبِي عَائِشَةَ ـ وَكَانَ ثِقَةً ـ عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا نَزَلَ عَلَيْهِ الْوَحْىُ حَرَّكَ بِهِ لِسَانَهُ ـ وَوَصَفَ سُفْيَانُ ـ يُرِيدُ أَنْ يَحْفَظَهُ فَأَنْزَلَ اللَّهُ ‏{‏لاَ تُحَرِّكْ بِهِ لِسَانَكَ لِتَعْجَلَ بِهِ‏}‏

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