1 Hear a just cause, O Lord; attend to my cry!
    Give ear to my prayer from lips free of deceit!
2 From your presence let my vindication come!
    Let your eyes behold the right!
3 You have tried my heart, you have visited me by night,
    you have tested me, and you will find nothing;
    I have purposed that my mouth will not transgress.
4 With regard to the works of man, by the word of your lips
    I have avoided the ways of the violent.
5 My steps have held fast to your paths;
    my feet have not slipped.
6 I call upon you, for you will answer me, O God;
    incline your ear to me; hear my words.

This psalm presents an interesting question: is this representative of a covenant individual or the covenant messiah? This individual is seemingly free from any sin. If read quite literally could this be applied to anyone but the messiah?
 
While these words are most clearly true of Jesus Christ, to remove them from the lips of a covenant individual defeats the intent of its song nature. These words are more true now in the realities of Jesus Christ but are to be sung by covenant people.

This is not self-righteousness since vindication comes from God (v. 1-2). This is not a works based redemption since God is deliverer (v. 1, 6).