Overall meaning : I swear by all that you can see, mankind, and all that you cannot see that this Qur’an is Allah’s Word, recited to you by a noble messenger—Muhammad. It is not at all the word of a poet, as you claim. How little faith you have! Nor is it the word of a soothsayer who falsely claims to know the unseen. How little heed you pay! This Qur’an is a revelation sent down from the Lord of all the worlds.
Had Muhammad invented lies and attributed them to Us, We would have punished him severely by Our power and severed his life vein! None of you, people, could have protected him from Allah’s punishment had he forged lies and attributed them to His Lord. Indeed, this Qur’an is a reminder and an admonition to the God-fearing who do what Allah commands and avoid what He forbids.
We know very well that there are some among you who deny it. It will be the source of bitter regret on Judgment Day for those who reject it. It is undeniably the absolute truth that has truly been sent down from Allah. Glorify, then, Muhammad, the name of your Lord, the All-Mighty, and declare Him free from all defects and imperfections!