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 Psalm 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.

Lift up thyself - Exert thy power.
Render a reward to the proud - To the Babylonians, who oppress and insult us.

Lift up thyself, thou, O Judge of the earth,.... A title very proper to Christ, and which is given him by Abraham, Genesis 18:25, who then appeared to him in an human form, and with whom he was conversing; he judges his own people on earth, all judgment being committed to him by the Father; he judges and chastises them, that they may not be condemned with the world; he judges and distinguishes between them and the world; he protects and defends them, he pleads their cause, and avenges them on their enemies: and for this purpose he is requested to "lift up" himself; being in the apprehension of his people as one laid down and asleep, quite negligent and careless of them; and therefore they desire that he would awake and arise, and exert his power, and show himself higher than their enemies; that he would mount his throne, and execute justice and judgment on the wicked, agreeably to his character and office:
render a reward to the proud; an evil reward, as the Targum; to proud persecutors of the church, who through their pride persecute the poor saints; and to render tribulation to them is but just with the Lord; to antichrist, that exalts himself above all that is called God, and to all his haughty and ambitious dependents and followers, cardinals, bishops, priests, &c.

Lift up thyself--or, "Arise," both figures representing God as heretofore indifferent (compare Psalm 3:7; Psalm 22:16, Psalm 22:20).