If Psalm 9 is a tribute to the justice of God, Psalm 10 is an admission of some troubling questions about that justice. What should we think when we observe God's justice to be missing?
The first 11 verses deal with the case of a prosperous wicked man. That the man is wicked is not in dispute. He hunts down the weak, he's boastful and proud, he ambushes and murders the innocent, and he is unconcerned about what God thinks of all this. Verse 5 tells us straight out that his ways are always prosperous and the next verse takes note of his complacency: "Nothing will shake me; I'll always be happy and never have trouble." What's wrong with this picture?
In verse 12, the Psalmist determines its his job to rouse the Lord. He reminds God of the situation at hand and calls for God to display some of His infamous vengeance. The final verses end with the Psalmist's assurance that it is only a matter of time until the Lord will do what He needs to do to dispense His justice.
This Psalm is a good reminder that injustice in the world isn't anything new, but it is temporary. While evil may appear to go unpunished for a frustratingly long time from our perspective, God is at work behind the scenes and can be trusted to render His verdict at the appropriate time.