Augustine. Exposition on the Book of Psalms. Schaff, Philip (editor). New York: Christian Literature Publishing Co, 1886. Nicene and Post-Nicene Church Fathers: Series 1: Volume VIII. Re-published 2014, Catholic Way Publishing. Kindle electronic edition, ISBN-13: 978-1-78379-372-3.
“Psalm 119: Gimel"
Verse 17 of Psalm 119 moves on from the desire for cleansing to ask God for a reward. Augustine identifies "four modes of reward: either evil for evil . . . or good for good . . . or good for evil . . . or evil for good" (Augustine Psalms, loc. 339040, par. 15). The most important is the third, when God gives good in return for evil, while the fourth is never practiced by God. The giving of good for evil is exemplified in verses 18-19, where, despite our failings, God lets us see how he gives good gifts (Augustine Psalms, loc. 339044, par. 17).
Augustine takes the language of verse 19, where the Psalmist is a "sojourner" on the earth, to refer not to the body, but to the soul. He sees the body to be earthly, but not the soul (Augustine Psalms, loc. 339049, par. 18). He sees the true home of the Christian to be a heavenly one. For this reason, if our desire is heavenly, he considers us to be here only temporarily. Freedom from this temporary existence is found through love for God and for the neighbor.
Verse 20 speaks of a positive type of coveting - having a desire for God's judgments. Augustine asserts "there is no obstacle to possessing the judgments of God, save that they are not desired" (Augustine Psalms, loc. 339061, par. 21).
The proud, in verse 21, wander away from God's commands. This is a clear sin, as it is through pride rather than weakness (Augustine Psalms, loc. 339065, par. 22). Augustine sees this as a terrible thing, as does the Psalmist, who, in verse 22, asks to be turned from shame and rebuke. This, again, is because of seeking God's word (Augustine Psalms, loc. 339070, par. 23). Rather than falling into rebuke by God, Augustine says we should be willing to face rebukie and even martyrdom at the hands of man.
In the end (vv. 23-24), the Psalmist lives in accord with God's word (Augustine Psalms, loc. 339082, par. 24).