(Reposted here in full because of brevity; original.)
This is the Path of Purity. The Hebrew word translated “cleanse” approaches the concept of moral transparency. How does a younger fellow allow others to see God through his life? In every generation, the young seldom give it much thought, and it requires developing strong habits — hedging his ways — with a heart-led awareness of God’s revelation. The psalmist claims that he is driven by a conviction, a personal commitment to please God.
To insure he reduces the opportunities for temptation, he hoards divine revelation in his heart. He finds Jehovah worthy of adoration, and waits for Him to goad him into obedience. How hard it is for the young!
With his own mouth he makes it a habit to affirm the moral judgments of God, talking often to himself about accountability. The Lord backs up His words; the psalmist delights in the moral wealth it brings him.
So finds himself pondering the message of revelation and how it makes so much sense of this crazy world. God keeps His own Word like a well-trodden path and the young man finds his own heart will not let him wander too far afield.