Sahih al-Bukhari 4927
صحيح البخاري#4927SahihNarrated Ibn `Abbas:The Prophet (ﷺ) used to move his tongue when the divine Inspiration was being revealed to him. (Sufyan, a subnarrator, demonstrated (how the Prophet (ﷺ) 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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 65:447