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 140 calls out to God as the one from whom we need mercy and grace. Augustine considers the ascription, pointing "to the end" as directing our attention to Christ. Furthermore, it says "to David Himself" which Augustine takes to direct us to Christ who sits on David's throne (Augustine Psalms, loc. 341941, par. 3).
Verse one calls out for deliverance from the wicked man. This, to Augustine, constitutes rescue from the works of the devil, who makes men wicked (Augustine Psalms, loc. 341947, par. 4). We pray for safety from all the works of evil, even if we think they are trivial. Augustine sees them to eventually lead to trouble. Verse two goes on to describe the unrighteousness coming from the heart. Augustine finds this as a secret place, where evil can lie concealed (Augustine Psalms, loc. 341961, par. 5). The essence, then, the true colors of the wicked, are shown in verse four, when the call is for preservation from sinners (Augustine Psalms, loc. 341971, par. 6). Augustine considers that many pray against certain practices or plots being used against them. However, it is the sinful nature which motivates it all.
In verse five, the sinful men are referred to as "the proud." Augustine describes the trap which the proud lay. "Hence it is that for the most part they call themselves righteous when they are unrighteous. Hence it is that nothing is so grievous to them as to confess their sins. They are men who, being falsely righteous, must needs envy the truly righteous" (Augustine Psalms, loc. 341986, par. 7). They try to trip up the righteous, as Augustine pictures it, with cords of sin (Augustine Psalms, loc. 341991, par. 8). Augustine continues by asking why God would have people try to cause his people to stumble. He concludes that the snares are off the path of righteousness. If we wish to keep from stumbling we need to remain on the way God has appointed us.
Verse six then calls out to God in prayer. There is a confidence to be found in submission to God (Augustine Psalms, loc. 342002, par. 9). Augustine understands this relationship with God to be that which makes the difference between mere sounds of prayer and powerful, living words of prayer. This is the prayer, which in verse seven, declares the Lord to be Lord and to give us strength (Augustine Psalms, loc. 342012, par. 10).
Verse eight continues to seek protection from sinners. Augustine describes the horrific things which have been done to martyrs, but then observes that "all this they did, yet did not God deliver them over to the sinners, because they were not delivered over by their own longing" (Augustine Psalms, loc. 342022, par. 11). When the devil invites us to join in his work, our will can stand in the way of his plan and guard us from being turned to the enemy. Those who are turned to evil are cornered by their own lips - the things they would say in their arrogance (v. 9). Augustine describes this as a "circle of error" where the journey doesn't end (Augustine Psalms, loc. 342031, par. 12). This is a hard way of life which, in verse ten, results in "coals of fire." Augustine takes this to be a hopeful reference, as fire is used for purification (Augustine Psalms, loc. 342042, par. 13).
Verse 11 describes the man who speaks too much and can't be guided. Augustine says that rather than being pleased by speaking we should wish to hear and learn (Augustine Psalms, loc. 342047, par. 14). H goes on to describe the appropriate times to speak - when there is a case which requires it or when an ignorant person wants to learn.
In verse 12 the Psalmist declares that "the Lord will maintain the right of the needy." Augustine emphasizes that this is the person who is aware of his need, who hungers and thirsts for righteousness, etc. (Augustine Psalms, loc. 342062, par. 15). The Lord makes this one a just person who confesses God's name. This is the protection of the righteous (Augustine Psalms, loc. 342067, par. 16).