To begin with, there are many verses in the Quran itself that underscore the majesty of Allah's verses and the Quran itself
Allah says (interpretation of the meaning):
Say: 'If the mankind and the jinn were together to produce the like of this Quran, they could not produce the like thereof, even if they helped one another'[Quran Al-Israa' 17:88]
Had We sent down this Quran on a mountain, you would surely have seen it humbling itself and rending asunder by the fear of Allah. Such are the parables which We put forward to mankind that they may reflect. [Quran Al-Hashr 59:21]
This is the Book (the Quran), whereof there is no doubt, a guidance to those who are Al-Muttaqoon [the pious] [Quran Al-Baqarah 2:2]