Ibn 'Abbas reported with regard to the words of Allah, Great and Glorious:
" Move not your tongue therewith" (Ixxv. 16) that when Gabriel brought revelation to him (the Prophet) he moved his tongue and lips (with a view to committing it to memory instantly). This was something hard for him and it was visible (from his face). Then Allah, the Exalted. revealed this a" Move not your tongue therewith to make haste (in memorising it). Surely on us rests the collecting of it and the reciting of it" (ixxv. 16), i. e. Verily it rests with Us that We would preserve it in your heart and (enable you) to recite it You would recite it when We would recite it and so follow its recitation, and He (Allah) said:" We revealed it, so listen to it attentively. Verily its exposition rests with Us. i. e. We would make it deliver by your tongue." So when Gabriel came to him (to the Prophet), he kept silence, and when he went away he recited as Allah had promised him.
وَحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، وَأَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ كُلُّهُمْ عَنْ جَرِيرٍ، - قَالَ أَبُو بَكْرٍ حَدَّثَنَا جَرِيرُ بْنُ عَبْدِ الْحَمِيدِ، - عَنْ مُوسَى بْنِ أَبِي عَائِشَةَ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، فِي قَوْلِهِ عَزَّ وَجَلَّ { لاَ تُحَرِّكْ بِهِ لِسَانَكَ} قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا نَزَلَ عَلَيْهِ جِبْرِيلُ بِالْوَحْىِ كَانَ مِمَّا يُحَرِّكُ بِهِ لِسَانَهُ وَشَفَتَيْهِ فَيَشْتَدُّ عَلَيْهِ فَكَانَ ذَلِكَ يُعْرَفُ مِنْهُ فَأَنْزَلَ اللَّهُ تَعَالَى { لاَ تُحَرِّكْ بِهِ لِسَانَكَ لِتَعْجَلَ بِهِ} أَخْذَهُ { إِنَّ عَلَيْنَا جَمْعَهُ وَقُرْآنَهُ} إِنَّ عَلَيْنَا أَنْ نَجْمَعَهُ فِي صَدْرِكَ . وَقُرْآنَهُ فَتَقْرَأُهُ { فَإِذَا قَرَأْنَاهُ فَاتَّبِعْ قُرْآنَهُ} قَالَ أَنْزَلْنَاهُ فَاسْتَمِعْ لَهُ { إِنَّ عَلَيْنَا بَيَانَهُ} أَنْ نُبَيِّنَهُ بِلِسَانِكَ فَكَانَ إِذَا أَتَاهُ جِبْرِيلُ أَطْرَقَ فَإِذَا ذَهَبَ قَرَأَهُ كَمَا وَعَدَهُ اللَّهُ .