The statutes of the LORD are right, rejoicing the heart: the commandment of the LORD is pure, enlightening the eyes.
Read Chapter 19
Augustine of Hippo
9. "The statutes of the Lord are right, rejoicing the heart" (ver. 8). All the statutes of the Lord are right in Him who taught not what He did not; that they who should imitate Him might rejoice in heart, in those things which they should do freely with love, not slavishly with fear. "The commandment of the Lord is lucid, enlightening the eyes." "The commandment of the Lord is lucid," with no veil of carnal observances, enlightening the sight of the inner man.
Justices. The law displays what is just, and renders those who observe it agreeable to God, (St. Gregory of Nazianzus) filling their hearts with joy, by the testimony of a good conscience, and the prospect of felicity. (Calmet) (Proverbs vi. 23.)