So the evil (consequences) of what they did shall afflict them and that which they mocked shall encompass them.

(In) behaving proudly in the land and in planning evil; and the evil plans shall not beset any save the authors of it. Then should they wait for aught except the way of the former people? For you shall not find any alteration in the course of Allah; and you shall not find any change in the course of Allah.

And the evil (consequences) of what they wrought shall become plain to them, and the very thing they mocked at shall beset them.

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

And the evil (consequences) of what they did shall become manifest to them and that which they mocked shall encompass them.