Sura al-Shūrā 42:52

وَكَذَٰلِكَ أَوْحَيْنَآ إِلَيْكَ رُوحًا مِّنْ أَمْرِنَا مَا كُنتَ تَدْرِى مَا ٱلْكِتَٰبُ وَلَا ٱلْإِيمَٰنُ وَلَٰكِن جَعَلْنَٰهُ نُورًا نَّهْدِى بِهِۦ مَن نَّشَآءُ مِنْ عِبَادِنَا وَإِنَّكَ لَتَهْدِىٓ إِلَىٰ صِرَٰطٍ مُّسْتَقِيمٍ

wa-ka-dhālika awḥaynā ilayka rūḥan min amrinā mā kunta tadrī mā l-kitābu wa-lā l-īmānu wa-lākin jaʿalnāhu nūran nahdī bihi man nashāʾu min ʿibādinā wainnaka la-tahdī ilā ṣirāṭin mustaqīmin

And thus have We, by Our Command, sent inspiration to thee: thou knewest not (before) what was Revelation, and what was Faith; but We have made the (Qur'an) a Light, wherewith We guide such of Our servants as We will; and verily thou dost guide (men) to the Straight Way,-