Repentance is of course important, but this poem is first about God’s righteousness, not my sin. The two of course are opposites, but there is a danger of self indulgence in wallowing if the rightness of God is not perceived in the poem. David is a good example of how to be wrong (2 Sam 11) and one that we still talk about. But the poet writes about something more that is able to deal with our troubles.