﴿ فِيهَا كُتُبٌۭ قَيِّمَةٌۭ ﴾

“wherein there are ordinances of ever-true soundness and clarity.”

wherein are upright precepts written rulings that are upright that is to say one who recites what contains all that and that is the Qur’ān. Thus some of them believed in it while others disbelieved.