Abdullah bin Abbas reported,

Regarding the saying of Allah , "Do not move your tongue with it to hasten it. Indeed, upon Us is its collection and its recitation" [Qiyamah 75:16–17], he said, "The Prophet ﷺ used to suffer great difficulty when revelation came down, and he would move his lips."Allah said, "Do not move your tongue with it to hasten it. Indeed, upon Us is its collection and its recitation" [Qiyamah 75:16–17].He said, "It means We will gather it in your chest, then you will recite it." "So when We have recited it, then follow its recitation" [Qiyamah 75:18]. He said, "Listen to it carefully and remain silent."So whenever Jibreel came to the Messenger of Allah ﷺ, he would listen, and once Jibreel departed, he would recite it just as Jibreel had recited it to him.

أخبرنا قتيبة قال حدثنا أبو عوانة عن موسى بن أبي عائشة عن سعيد بن جبير

عن ابن عباس

في قوله عز وجل {لا تحرك به لسانك لتعجل به إن علينا جمعه وقرآنه} قال كان النبي ﷺ يعالج من التنزيل شدة وكان يحرك شفتيه قال الله عز وجل {لا تحرك به لسانك لتعجل به إن علينا جمعه وقرآنه} قال جمعه في صدرك ثم تقرؤه {فإذا قرأناه فاتبع قرآنه} قال فاستمع له وأنصت فكان رسول الله ﷺ إذا أتاه جبريل استمع فإذا انطلق قرأه كما أقرأه