Of all the Psalms of repentance, this is the most well-known. David had committed adultery and had an innocent man killed. The Prophet, Nathan, pointed his finger at David revealing that his sin was not hidden from God. This passionate plea for mercy would follow.
This prayer which passes through David's lips has poured from the hearts of many contrite sinners. His prayer of repentance has become our model and textbook on the subject.
David's appeal for forgiveness is not based on the good he had done to outweigh the bad. He is not making a deal with God. Rather, he appeals to God's "tender mercies" (v.1), His love and compassion. As with David, this is our hope for forgiveness.