How do we know that prayer includes confession of sins?

In Psalm 25, David explicitly acknowledges the necessity of confessing sins as part of prayer. He asks God to remember not his youthful sins and pleads for pardon for his iniquity. This highlights that, while all sins of believers are forgiven through Christ, daily confession is vital for maintaining a clear conscience and relationship with God. The act of confession allows us to experience the forgiveness already granted through Christ's sacrifice, reinforcing our dependence on God's mercy.