Albert Barnes Commentary Job 40:12

"Look on every one that is proud, [and] bring him low; And tread down the wicked where they stand." — Job 40:12 (ASV)

And tread down the wicked in their place— Even in the very place where they are, crush them to the dust, as God can. It is implied that God was able to do this, and he appeals to it as a proof of his power.