Jurists discuss the verse لَا يَمَسُّهُ إِلَّا الْمُطَهَّرُونَ
Meaning: None touches it except the purified.
They also cite لَا يَمَسُّ الْقُرْآنَ إِلَّا طَاهِرٌ
Meaning: None may touch the Qur’an except one who is pure.
The verse has exegetical discussion regarding its referent; legal reasoning also includes the hadith and wider evidence.