Quran 7:184 — The Purgatory (Al-A'araf)

Why do they not reflect upon their friend (the messenger)? He is not crazy. He is simply a profound warner.

[7:183] I will even encourage them; My scheming is formidable.

[7:185] Have they not looked at the dominion of the heavens and the earth, and all the things GOD has created? Does it ever occur to them that the end of their life may be near? Which Hadith, beside this, do they believe in?