إِلَّا رَحْمَةً مِّن رَّبِّكَ ۚ إِنَّ فَضْلَهُۥ كَانَ عَلَيْكَ كَبِيرًا
28:87.
Commentary:
The meaning of the expression, Surely, His grace towards thee is great, among other things, is that when the spirit of the Quran disappeared from the world and its letter only remained, God alone could and would bring it back.
28:87.