Surah Ash Shu'ara Tafseer

وَمَا يَنبَغِي لَهُمْ

Neither would it suit them,

وَمَا يَسْتَطِيعُونَ

nor are they able.

meaning, even if they wanted to, they could not do it.

Allah says:

لَوْ أَنزَلْنَا هَـذَا الْقُرْءَانَ عَلَى جَبَلٍ لَّرَأَيْتَهُ خَـشِعاً مُّتَصَدِّعاً مِّنْ خَشْيَةِ اللَّهِ

Had We sent down this Qur'an on a mountain, you would surely have seen it humbling itself and rent asunder by the fear of Allah. (59:21)

Then Allah explains that even if they wanted to and were able to bear it and convey it, they still would not be able to achieve that, because they were prevented from hearing the Qur'an when it was brought down, for the heavens were filled with guardians and shooting stars at the time when the Qur'an was being revealed to the Messenger of Allah, so none of the Shayatin could hear even one letter of it, lest there be any confusion in the matter.

This is a part of Allah's mercy towards His servants, protection of His Laws, and support for His Book and His Messenger.

Allah says:

إِنَّهُمْ عَنِ السَّمْعِ لَمَعْزُولُونَ