Albert Barnes' Bible Commentary
Psalms 19:9
The fear of the Lord - The word rendered fear in this place - יראה yir'âh - means properly fear, terror, Jonah 1:10; then, reverence, or holy fear, Psalms 2:11; Psalms 5:7; and hence, reverence toward God, piety, religion - in which sense it is often used. Compare Proverbs 1:7; Job 28:28; Isaiah 11:2. Hence, by metonymy, it means the precepts of piety or religion. It is used evidently in this sense here, as referring to revelation, or to revealed truth, in the sense that it promotes proper reverence for God, or secures a proper regard for his name and worship.
Is clean - The word used here - טהור ṭâhôr - means properly clear, pure, in a physical sense, as opposed to filthy, soiled; then, in a ceremonial sense, as opposed to that which is profane or common Leviticus 13:17, and then, in a moral sense, as a clean heart, etc., Psalms 12:6; Psalms 51:10. It is also applied to pure gold, Exodus 25:11. The sense here is, that there is nothing in it that tends to corrupt the morals, or defile the soul. Everything connected with it is of a pure or holy tendency, adapted to cleanse the soul and to make it holy.
Enduring for ever - Standing to all eternity. Not temporary; not decaying; not destined to pass away. It stands firm now, and it will stand firm for ever. That is, the law of God, considered as adapted to make the heart holy and pure, is eternal. What it is now it will always be. What its teaching is now it will continue to be forever.
The judgments of the Lord - The word here rendered judgments refers also to the revealed truth of God, with the idea that that has been judged or determined by him to be right and to be best. It is the result of the divine adjudication as to what is true, and what is best for man. The word is often used in this sense. Compare Exodus 21:1; Leviticus 18:5; Leviticus 26:43; compare Psalms 9:7, Psalms 9:16; Psalms 10:5.
Are true - Margin, truth. So the Hebrew. That is, they accord entirely with the truth, or are a correct representation of the reality of things. They are not arbitrary, but are in accordance with what is right. This supposes that there is such a thing as truth in itself, and the divine law conforms to that; not that God determines a thing by mere will, and that it is, therefore, right. God is infinitely perfect, and what he does will be always right, for that is in, accordance with his nature; but still his judgments are right, not because he makes that to be right which is determined by his will, but because his will is always in accordance with what is right.
And righteous altogether - That is, they are, without exception, just; or, they are altogether or wholly righteous. There is no one of them which is not just and proper. All that God determines, whether in giving or in executing his laws - all in his requirements, and all in the administration of his government - is always and wholly righteous. It is precisely what it should be in the case, and is, therefore, worthy of universal confidence.