John Wesley on Psalms 19:9

The fear - The law and word of God, because it is both the object and the rule, and the cause of holy fear. Clean - Sincere, not adulterated with any mixture. Constant and unchangeable, the same for substance in all ages. Judgments - God's laws are frequently called his judgments, because they are the declarations of his righteous will, and as it were his judicial sentence by which he expects that men should govern themselves, and by which he will judge them at the last day.