Narrated Said bin Jubair:
Ibn 'Abbas in the explanation of the Statement of Allah. 'Move not your tongue concerning (the Quran) to make haste therewith." (75.16) Said "Allah's Apostle used to bear the revelation with great trouble and used to move his lips (quickly) with the Inspiration." Ibn 'Abbas moved his lips saying, "I am moving my lips in front of you as Allah's Apostle used to move his." Said moved his lips saying: "I am moving my lips, as I saw Ibn 'Abbas moving his." Ibn 'Abbas added, "So Allah revealed 'Move not your tongue concerning (the Qur'an) to make haste therewith.