Cast abroad the rage of thy wrath - That is, as God does. Show that the same effects can be produced by "your" indignation which there is in his. God appeals here to the effect of his displeasure in prostrating his foes as one of the evidences of his majesty and glory, and asks Job, if he would compare himself with him, to imitate him in this, and produce similar effects.
And behold every one that is proud, and abase him - That is, "look" upon such an one and bring him low, or humble him by a look. It is implied here that God could do this, and he appeals to it as a proof of his power.

Cast abroad the rage of thy wrath,.... Work thyself up into a passion, at least seemingly; put on all the airs of a wrathful and enraged king on a throne of state, whose wrath is like the roaring of a lion, and as messengers of death; pour out menaces plentifully, threatening what thou wilt do; and try if by such means thou canst humble the spirit of a proud man, as follows;
and behold everyone that is proud, and abase him; look sternly at him, put on a fierce, furious, and menacing countenance, and see if thou canst dash a proud man out of countenance, and humble him before thee, as I am able; among the many instances of divine power the Lord settles upon this one, and proposes it to Job to try his skill and power upon, the humbling of a proud man.

rage--rather, pour out the redundant floods of, &c.
behold--Try, canst thou, as God, by a mere glance abase the proud (Isaiah 2:12, &c.)?