وَأَيْقَنُوا أَنَّهُ كَلَامُ اللَّهِ تَعَالَى بِالْحَقِيقَةِ
They were certain that it is truly the speech of Allah Most High.
In reality clarifies that the attribution of the Qur’an to Allah is not merely a symbolic title.
Certainty entails affirming this true relation of divine speech and avoiding claims that deny it.