St. Augustin on the Psalms.
143. ...He who singeth this Psalm, mentioneth such a prayer of his own: "I have called with my whole heart; hear me, O Lord!" (ver.145). For to what end his cry profiteth, he addeth: "I will search out Thy righteousnesses." For this purpose then he hath called with his whole heart, and hath longed that this might be given him by the Lord listening unto him, that he may search out His righteousnesses...
144. "I have called, save me" (ver.146) or as some copies, both Greek and Latin, have it, "I have called to Thee." But what is, "I have called to Thee," save that by calling I have invoked Thee? But when he had said, "save me;" what did he add? "And I will keep Thy testimonies:" that is, that I may not, through infirmity, deny Thee. For the health of the soul causeth that to be done which it is known to be our duty to do, and thus in striving even to the death of the body, if the extremity of temptation demand this in defence of the truth of the divine testimonies: but where there is not health of the soul, weakness yieldeth, and truth is deserted...
145. "I have prevented in midnight," he saith, "and have cried: In Thy words have I trusted" (ver.147). If we refer this to each of the faithful, and to the literal character of the act; it oft happeneth that the love of God is awake in that hour of the night, and, the love of prayer strongly urging us, the time of prayer, which is wont to be after the crowing of the cock, is not awaited, but prevented. But if we understand night of the whole of this world's duration; we indeed cry unto God at midnight, and prevent the fulness of time in which He will restore us what He hath promised, as is elsewhere read, "Let us prevent His presence with confession."  Although if we choose to understand the unripe season of this night, before the fulness of time had come,  that is, the ripe season when Christ should be manifested in the flesh; neither was the Church then silent, but preventing this fulness of time, in prophecy cried out, and trusted in the words of God, who was able to do what He promised, that in the seed of Abraham all nations should be blessed. 
146. The Church saith also what followeth, "Mine eyes have prevented the morning watch, that I might meditate on Thy words" (ver.148). Let us suppose the morning to mean the season when "a light arose for them that sat in the shadow of death;"  did not the eyes of the Church prevent this morning watch, in those Saints who before were on earth, because they foresaw beforehand that this would come to pass, so that they meditated on the words of God, which then were, and announced these things to be destined in the Law and the Prophets?
147. "Hear my voice, O Lord, according to Thy loving-mercy; and quicken Thou me according to Thy judgment" (ver.149). For first God according to His loving-mercy taketh away punishment from sinners, and will give them life afterwards, when righteous, according to His judgment; for it is not without a meaning that it is said unto Him, "My song shall be of mercy and judgment: unto Thee, O Lord;"  in this order of the terms: although the season of mercy itself be not without judgment, whereof the Apostle saith, "If we would judge ourselves, we should not be judged of the Lord."  ...And the final season of judgment shall not be without mercy, since as the Psalm saith, "He crowneth thee with mercy and loving-kindness." But "judgment shall be without mercy," but "unto those" on the left, "who have not dealt mercy." 
148. "They draw nigh, that of malice persecute me:" or, as some copies read, "maliciously" (ver.150). Then they that persecute draw nigh, when they go the length of torturing and destroying the flesh: whence the twenty-first Psalm, wherein the Lord's Passion is prophesied, saith, "O go not from me, for trouble is hard at hand;"  where those things are spoken of which He suffered when His Passion was not imminent upon Him, but actually realized. "And are far from Thy law." The nearer they drew to the persecuting the righteous, so much the farther were they from righteousness. But what harm did they do unto those, to whom they drew near by persecution; since the approach of their Lord is nearer unto their souls, by whom they no wise are forsaken?
149. Lastly, it followeth, "Thou art nigh at hand, O Lord, and all Thy ways are truth" (ver.151). Even in their troubles, it hath been a wonted confession of the saints, to ascribe truth unto God, because they suffer them not undeservedly. So did Queen Esther,  so did holy Daniel,  so did the three men in the furnace,  so do other associates in their sanctity confess. But it may be asked, in what sense it is here said, "All Thy ways are truth;" since in another Psalm it is read, "All the ways of the Lord are mercy and truth."  But towards the saints, All the ways of the Lord are at once mercy and truth: since He aideth them even in judgment, and thus mercy is not wanting; and in having mercy upon them, He performeth that which He hath promised, so that truth is not wanting. But towards all, both those whom He freeth, and those whom He condemneth, all the ways of the Lord are mercy and truth; because where He doth not show mercy, the truth of His vengeance is displayed. For He freeth many who have not deserved, but He condemneth none who hath not deserved it.
150. "From the beginning I have known," he saith, "as concerning Thy testimonies, that Thou hast grounded them for ever"  (ver.152)...What are these testimonies, save those wherein God hath declared that He will give an everlasting kingdom unto His sons? And since He hath declared that He will give this in His only-begotten Son, he said that the testimonies themselves were grounded for ever. For that which God hath promised through them, was everlasting. And for this reason the words, "Thou hast grounded them," are rightly thus understood, because they are shown to be true in Christ.  Whence then did the Psalmist know this in the beginning, save because the Church speaketh, which was not wanting to the earth from the commencement of the human race, the first-fruits whereof was the holy Abel, himself sacrificed in testimony of the future blood of the Mediator that should be shed by a wicked brother?  For this also was at the beginning, "They two shall be one flesh:"  which great mystery the Apostle Paul expounding, saith, "I speak concerning Christ and the Church." 
 Psalm 95:2.  Galatians 4:4.  Genesis 12:3 and xxii. 18.  Isaiah 9:2.  Psalm 101:1.  1 Corinthians 11:31.  James 2:13.  Psalm 22:11.  Esth. 14. 6, 7.  Daniel 9:4, 16.  Song of 3-Chil. 2-10.  Psalm 25:10.  [Here the author says: "The Greek word katarchas hath been variously rendered by the Latin translators by ab initio, initio, and in initiis. Those who rendered it in the plural, have followed the Greek phrase. But it is more usual in the Latin tongue to express the idea conveyed by katarchas, which in the Greek is used in the plural or adverbially, by the words ab initio, or initio; just as with us, when we say, Otherwise I do this (alias hoc facio), we seem to be using the plural of the feminine gender, whereas the word is an adverb, and signifies, at another time."--C.]  1 Corinthians 3:11.  Genesis 4:8.  Genesis 2:24.  Ephesians 5:32.
 Galatians 4:4.
 Genesis 12:3 and xxii. 18.
 Isaiah 9:2.
 Psalm 101:1.
 1 Corinthians 11:31.
 James 2:13.
 Psalm 22:11.
 Esth. 14. 6, 7.
 Daniel 9:4, 16.
 Song of 3-Chil. 2-10.
 Psalm 25:10.
 [Here the author says: "The Greek word katarchas hath been variously rendered by the Latin translators by ab initio, initio, and in initiis. Those who rendered it in the plural, have followed the Greek phrase. But it is more usual in the Latin tongue to express the idea conveyed by katarchas, which in the Greek is used in the plural or adverbially, by the words ab initio, or initio; just as with us, when we say, Otherwise I do this (alias hoc facio), we seem to be using the plural of the feminine gender, whereas the word is an adverb, and signifies, at another time."--C.]
 1 Corinthians 3:11.
 Genesis 4:8.
 Genesis 2:24.
 Ephesians 5:32.