Whenever the Quran was revealed to the Messenger of Allah ﷺ, he would move his tongue with it, eager to memorize it. So Allah revealed, "Do not move your tongue with it to hasten with it" [Qiyamah 75:16].He said, He used to move his lips with it. And Sufyan moved his own lips to demonstrate.
حدثنا ابن أبي عمر حدثنا سفيان بن عيينة عن موسى بن أبي عائشة عن سعيد بن جبير
كان رسول الله ﷺ إذا أنزل عليه القرآن يحرك به لسانه يريد أن يحفظه فأنزل الله {لا تحرك به لسانك لتعجل به} قال فكان يحرك به شفتيه وحرك سفيان شفتيه
Agreed upon. Bukhari reported it in the Book of Tafsir, chapter "Do not move your tongue with it to hasten with it," hadith no. 4927, from the hadith of Sufyan bin Uyayna. Muslim reported it, hadith no. 448, from the hadith of Musa bin Abu Ayesha.