إِنّا نَحنُ نَزَّلنا عَلَيكَ القُرآنَ تَنزيلًا

Indeed We have sent down to you the Quran in a gradual descent.

EXEGESIS

Innā naḥnu nazzalnā (indeed we have sent down) is an expression that can be dissected into three parts: innā (verily we), naḥnu (we), and nazzalnā (we sent down). Without naḥnu (we) in the expression, innā nazzalnā means: verily we have sent down, with the extra emphasis from ‘verily’. Adding naḥnu to innā places even more emphasis. Hence, instead of the verse saying: We sent down to you the Quran, it is saying: Indeed, it is verily Us who have sent down to you the Quran. This high emphasis comes to stress that the source of these revelations is God alone without any satanic or personal interference.^{‎[1]Razi, 30/758.}

[1] Razi, 30/758.