And they planned and Allah (also) planned, and Allah is the best of planners.

And they have indeed planned their plan, but their plan is with Allah, though their plan was such that the mountains should pass away thereby.

Do they then who plan evil (deeds) feel secure (of this) that Allah will not cause the earth to swallow them or that punishment may not overtake them from whence they do not perceive?

And they planned a plan, and We planned a plan while they perceived not.

So Allah protected him from the evil (consequences) of what they planned, and the most evil punishment overtook Firon's people:

And they have planned a very great plan.