Nay, the Hour (of Judgment) is the time promised them (for their full recompense):(5160) And that Hour will be most grievous and most bitter.
5160 The calculations of unjust men—on their science, their resources, their numbers, etc.—will in many cases be falsified even in this world, as stated in the last two verses, but their real Punishment will come with Judgement, i.e., when they find their real place in the spiritual world at the restoration of true values. It will then be a most grievous and bitter experience for them, throwing into the shade any calamities they may suffer in this life.