Authority of the Quran

الٓر ۚ تِلْكَ ءَايَـٰتُ ٱلْكِتَـٰبِ ٱلْحَكِيمِ

Alif, Lām, Rā. These are the verses of the wise Book.

أَمْ لَكُمْ كِتَـٰبٌ فِيهِ تَدْرُسُونَ

Or do you have a scripture in which you learn