St. Augustin on the Psalms.
1. ...The title of the Psalm is, "To David himself, when his son was pursuing him." We know from the Books of Kings  that this happened:...but we must recognise here another David, truly "strong in hand," which is the explanation of David, even our Lord Jesus Christ. For all those events of past time were figures of things to come. Let us seek then in this Psalm our Lord and Saviour Jesus Christ, announcing Himself beforehand in His prophecy, and foretelling what should happen at this time by things which were done long ago. For He Himself foretold Himself in the Prophets: for He is the Word of God. Nor did they say ought of this kind, save when filled with the Word of God. They announced then Christ, being filled with Christ,  they went before Him about to come, and He deserted not them going before....
2. Let then our Lord speak; let Christ with us, whole Christ, speak. "Lord, hear my prayer, receive with Thine ears my entreaty" (ver.1). "Hear" and "receive with ears" are the same thing. It is repetition, it is confirmation. "In Thy truth hear me, in Thy righteousness." Take it not without emphasis when it is said, "in Thy righteousness." For it is a commendation of grace, that none of us think his righteousness his own. For this is the righteousness of God, which God hath given thee to possess. For what saith the Apostle of them, who would boast of their own righteousness? Speaking of the Jews, he saith, "they have a zeal of God, but not according to knowledge."  ...Thou art perverse, because thou imputest what thou hast done ill to God, what well to thyself: thou wilt be right, when thou imputest what thou hast done ill to thyself, what well to God....Behold, "in Thy righteousness hear me." For when I look upon myself, nought else do I find mine own, save sin.
3. "And enter not into judgment with Thy servant" (ver.2). Who are willing to enter into judgment with Him, save they who, "being ignorant of the righteousness of God, go about to establish their own?" "Wherefore have we fasted, and Thou hast not seen; wherefore have we afflicted our souls, and Thou takest no knowledge?"  As though they would say, "We have done what Thou hast commanded, wherefore dost Thou not render to us what Thou hast promised?" God answereth thee: I will give to thee to receive what I have promised: I have given thee that thou shouldest do that whereby thou mayest receive. Finally, to such proud ones the Prophet speaketh; "Wherefore will ye plead with Me? ye have all transgressed against Me, saith the Lord."  Why will ye enter into judgment with Me, and recount your own righteousnesses?..."For before Thee every one living shall not be justified." "Every one living;" living, that is, here, living in the flesh, living in expectation of death; born a man; deriving his life of man; sprung from Adam, a living Adam; every one thus living may perhaps be justified before himself, but not before Thee. How before himself? By pleasing himself, displeasing Thee. Enter not then into judgment with me, O Lord my God. How straight soever I seem to myself, Thou bringest forth a standard from Thy store-house, Thou fittest me to it, and I am found crooked. Well is it said, "with Thy servant." It is unworthy of Thee to enter into judgment with Thy servant, or even with Thy friend.  ...What of the Apostles themselves?...That ye may perceive it at once, they learnt to pray what we pray: to them was given the pattern of prayer by the heavenly Counsellor. "After this manner," saith He, "pray ye."  And having set down certain things first, He laid down this too to be said by the leaders of the sheep, the chief members of the Shepherd and Gatherer  of the one flock; even they learnt to say, "Forgive us our debts."  They said not, "Thanks be to Thee, who hast forgiven us our debts, as we too forgive our debtors," but, "Forgive, as we forgive." But surely the faithful prayed then, surely the Apostles prayed then, for this Lord's Prayer was given rather to the faithful. If those debts only were meant which are forgiven by Baptism, it would befit catechumens rather to say, "Forgive us our debts." Let the Apostles then say, yea let them say, "Forgive us our debts." And when it is said to them, "Wherefore say ye this? what are your debts?" let them answer, "for in Thy sight every one living shall not be justified."
4. "For the enemy hath persecuted my soul: he hath humbled my life on the earth" (ver.3). Here we speak, here our Head speaketh for us. Manifestly both the devil persecuted the Soul of Christ and Judas the Soul of his Master: and now too the same devil remaineth to persecute the Body of Christ, and one Judas succeedeth another. There lacketh not then of whom the Body too may say, "For the enemy hath persecuted my soul." For what doth each one who persecuteth us endeavour save to make us abandon our heavenly hope, and savour of the earth, yield to our persecutor, and love earthly things? "They have laid me in dark places, as the dead of the world." This ye hear more readily from the Head; this ye perceive more readily in the Head. For He died indeed for us, yet was He not one of the "dead of the world." For who are the "dead of the world"? And how was not He one of the "dead of the world"? "The dead of the world" are those who have died of their own desert, receiving the reward of iniquity, deriving death from the sin transmissed to them; according as it is said, "For I was conceived in iniquity."  ...In dying, saith He, I do the will of My Father, but I am not deserving of death. Nought have I done wherefore I should die, yet is it Mine own doing that I die, that by the death of an innocent One, they may be freed who had wherefore they should die. "They set me in places," as though in Hades, as though in the tomb, as though in His very Passion, "as the dead of the world." 
5. "And My Spirit within me," saith He, "suffered weariness" (ver.4). Remember, "My soul is exceeding sorrowful, even unto death."  Here we see one voice. Do we not see plainly the transition from the Head to the members, from the members to the Head?...
6. But we too were there. He goes to the members. "I have called to mind the days of old" (ver.5). Did He "call to mind the days of old," by whom every day was made? No, but the body speaketh, each one who has been justified by His grace, who dwelleth in Him in love and devout humility, speaketh and saith, "I have meditated upon all Thy works:" plainly because Thou hast made all things good, and nothing would have stood fast, which was not established by Thee. Thy creation is made a spectacle unto me: I have sought in the work the Artificer, in all that is made the Maker. Wherefore this, to what purpose this, save that he might understand, that whatever there was of good in himself was made by Him....Look back then upon the Framer of thy life, the Author of thy substance, of thy righteousness, and of thy salvation: "meditate upon the works of His hands," for the righteousness too which is in thee, thou wilt find to pertain to His hand. Hear the Apostle teaching thee this, "not of works," he saith, "lest any should boast." Have we no good works? Plainly we have: but see what follows; "for we are His workmanship,"  saith he. "We are His workmanship:" perhaps in thus speaking of workmanship, he meant to mention the nature whereby we are men? Evidently not: he was speaking of works. But let us not make conjectures; let the text go on, "for we are His workmanship, created in Christ Jesus unto good works." Think not then that thou thyself doest anything, save in so far as thou art evil...."Work out your own salvation," saith the Apostle, "with fear and trembling."  If we do work out our own salvation, wherefore with fear, wherefore with trembling, when what we work is in our own power? Hear wherefore with fear and trembling: "for it is God that worketh in you both to will and to do, of His good pleasure." Therefore "with fear and trembling," that it may delight our Maker to work in the lowly valley....
7. "I stretched forth," saith he, "my hands to Thee: my soul is as a land without water to Thee" (ver.6). Rain upon me, saith he, to bring forth from me good fruit. "For the Lord shall give sweetness, that our land may give her fruit."  "I have stretched forth my hands to Thee; my soul is as a land without water," not to me, but "to Thee." I can thirst for Thee, I cannot water myself.
8. "Speedily hear me, Lord" (ver.7). For what need of delay to inflame my thirst, when already I thirst so eagerly? Thou didst delay the rain, that I might drink and imbibe, not reject, Thy inflowing. If then Thou didst for this cause delay, now give; for "my spirit hath failed." Let Thy Spirit fill me. This is the reason why Thou shouldest speedily hear me. I am now become "poor in spirit," make Thou me "blessed in the kingdom of heaven."  For he in whom his own spirit liveth, is proud, is puffed up with his own spirit against God....
9. "Turn not Thou away Thy Face from me." Thou didst turn it away from me when proud. For once I was full, and in my fulness I was puffed up. Once "in my fulness I said, I shall never be moved." "I said in my fulness, I shall not be moved," knowing not Thy Righteousness, and establishing mine own; but "Thou, Lord, in Thy Will hast afforded strength to my beauty." "I said in my fulness, I shall not be moved," but from Thee came whatever fulness I had. And to prove to me that it was from Thee, "Thou didst turn away Thy Face from me, and I was troubled."  After this trouble, where into I was cast, because Thou didst turn away Thy Face, after the weariness of my spirit, after my heart was troubled within me, because Thou didst turn away Thy Face, then became I "like a land without water to Thee: turn not Thou away Thy Face." Thou turnedst it away from me when proud; give it back to me now I am humble. Because, if Thou turn it away, "I shall be like to them that go down into the pit." What is, "that go down into the pit"? When the sinner has come into the depth of sins, he will show contempt. They "go down into the pit," who lose even confession; against which is said, "Let not the pit close her mouth over me."  This depth Scripture calleth mostly "a pit," into which depth when a sinner hath come, "he showeth contempt." What is, "he showeth contempt"? He no longer believeth in Providence, or if he do believe, he thinketh that he has no longer aught to do with it....
10. "Make me to hear in the morning Thy mercy, for in Thee have I hoped" (ver.8). Behold, I am in the night, yet "in Thee have I hoped," until the iniquity of the night pass away. "For we have," as Peter saith, "a more sure word of prophecy, whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the daystar arise in your hearts." "Morning" then he calleth the time after the end of the world, when we shall see what in this world we believe. But what here, until the morning come? For it is not enough to hope for the morning; we must do somewhat. Why do somewhat? God is to be sought with the hands in the night. What is, "with the hands"? By good works. Since then we must thus hope for the morning, and bear this night, and persevere in this patience until the day dawn, what meanwhile must we do here? lest perchance thou think that thou wilt do aught of thyself, whereby thou mayest earn to be brought to the morning. "Make known to me, O Lord, the way wherein I must walk." Therefore did He kindle the lamp of prophecy, therefore did He send the Lord in the vessel,  as it were, of the flesh, who should even say, "My strength is dried up like a potsherd."  Walk by prophecy, walk by the lamp of future things predicted, walk by the word of God....
11. "Deliver me from mine enemies, O Lord, for unto Thee have I fled for refuge" (ver.9). I who once fled from Thee, now flee to Thee. For Adam fled from the Face of God, and hid himself among the trees of Paradise, so that of him was said in the Book of Job, "As a servant that fleeth from his Lord, and findeth a shadow."  He fled from the Face of his Lord, and found a shadow. Woe to him, if he continue in the shade, lest it be said afterward, "All things are passed away like a shadow."  The rulers of this world, of this darkness, the rulers of the wicked; against these ye wrestle. Great is your conflict, not to see your enemies, and yet to conquer. Against the rulers of this world, of this darkness, the devil, that is, and his angels; not the rulers of that world, whereof is said, "the world was made by Him," but that world whereof is said, "the world knew Him not."  "For unto Thee have I fled for refuge."...Whither should I flee? "Whither shall I go from Thy Spirit?" 
12. "Teach me to do Thy will, for Thou art my God" (ver.10). Glorious confession! glorious rule! "For Thou," saith he, "art my God." To another will I hasten to be re-made, if by another I was made. Thou art my all, "for Thou art my God." Shall I seek a father to get an inheritance? "Thou art my God," not only the Giver of mine inheritance, but mine Inheritance itself. "The Lord is the portion of mine inheritance."  Shall I seek a patron, to obtain redemption? "Thou art my God." Lastly, having been created, do I desire to be re-created? "Thou art my God," my Creator, who hast created me by Thy Word, and re-created me by Thy Word. "Teach Thou me:" for it cannot be that Thou art my God, and yet I am to be mine own master. See how grace is commended to us. This hold fast, this drink in, this let none drive out of your hearts, lest ye have "a zeal, of God, but not according to knowledge."  Say then this: "Thy good Spirit," not my bad one, "Thy good Spirit shall lead me into the right land." For my bad spirit hath led me into a crooked land. And what have I deserved? What can be reckoned as my good works without Thy aid, through which I might obtain and be worthy to be led by Thy Spirit into the right land?
13. Listen, then, with all your power, to the commendation of Grace, whereby ye are saved without price. "For Thy Name's sake, O Lord, Thou shalt quicken me in Thy righteousness" (ver.11); not in mine own: not because I have deserved, but because Thou hast mercy. For were I to show mine own desert, nought should I deserve of Thee, save punishment. Thou hast pruned off from me mine own merits; Thou hast grafted in Thine own gifts. "Thou shalt bring forth my soul out of tribulation." "And in thy mercy shalt bring mine enemies to destruction: and thou shalt destroy all them that afflict my soul; for I am Thy servant" (ver.12).
 Lat. CXLII. A sermon to the people.  2 Samuel 15.p> [1 Pet. i. 10, 11, 12.--C.]  Romans 10:2.  Isaiah 58:3.  Jeremiah 2:29.  Matthew 5:40.  Matthew 6:9.  Congregatoris; mss. Congregatores, The gatherers.  Matthew 6:12.  Psalm 51:5.  Psalm 38:4, 5.  Matthew 26:38.  Ephesians 2:9, 10.  Philip. ii. 12, 13.  Psalm 85:12.  Matthew 5:3.  Psalm 30:6, 7.  Psalm 69:15.  Testâ.  Psalm 22:15.  Job 7:2, LXX.  Wisd. v. 9.  John 1:10.  Psalm 139:7.  Psalm 16:5.  Romans 10:2.
 2 Samuel 15.p> [1 Pet. i. 10, 11, 12.--C.]
 Romans 10:2.
 Isaiah 58:3.
 Jeremiah 2:29.
 Matthew 5:40.
 Matthew 6:9.
 Congregatoris; mss. Congregatores, The gatherers.
 Matthew 6:12.
 Psalm 51:5.
 Psalm 38:4, 5.
 Matthew 26:38.
 Ephesians 2:9, 10.
 Philip. ii. 12, 13.
 Psalm 85:12.
 Matthew 5:3.
 Psalm 30:6, 7.
 Psalm 69:15.
 Psalm 22:15.
 Job 7:2, LXX.
 Wisd. v. 9.
 John 1:10.
 Psalm 139:7.
 Psalm 16:5.
 Romans 10:2.