Lift up thyself - Be exalted or lifted up so as to be manifest in thy true character. The idea is that God was, as it were, sitting at his ease, or as if he were indifferent to what was occurring in the world. See the notes at Psalms 3:7.
Thou Judge of the earth - Ruler of the world; to whom it pertains to exercise judgment over all classes of people, and in all circumstances. The meaning here is, that as he was the Ruler of the whole earth, this matter came without doubt under his jurisdiction. It was a case for his interposition.
Render a reward to the proud - A just recompence to the people who are confident in their own strength, and who are manifesting their pride in depriving others of their rights.