13 But let us see now another way in which this sentence may be understood. There is a certain iniquity, on the worker whereof it cannot be that God have mercy. You enquire, perchance, what that is? It is the defending of sins. When a man defends his sins, great iniquity he works: that thing he is defending which God hates. And see how perversely, how iniquitously. Whatever of good he has done, to himself he would have it to be ascribed; whatever of evil, to God. For in this manner men defend sins in the person of God, which is a worse sin....Therefore you defend your sin in such sort, that you lay blame on God. So the guilty is excused, so that the Judge may be charged. However on men working iniquity God has no pity at all.
14. “Let them be converted at the evening”. Of certain men he is speaking that were once workers of iniquity, and once darkness, being converted in the evening. What is, “in the evening”? Afterward. What is “at the evening”? Later. For before, before that they crucified Christ, they ought to have acknowledged their Physician. Wherefore, when He had been crucified— rising again, into Heaven ascending— after that He sent His Holy Spirit, wherewith were fulfilled they that were in one house, and they began to speak with the tongues of all nations, there feared the crucifiers of Christ; they were pricked through with their consciences, they besought counsel of safety from the Apostles, they heard, “Repent, and be baptized each one of you in the name of our Lord Jesus Christ, and your sins shall be remitted unto you.” After the slaying of Christ, after the shedding of the blood of Christ, remitted are your sins....“Let these be converted,” therefore, they also “at evening.” Let them yearn for the grace of God, perceive themselves to be sinners; let those strong men be made weak, those rich men be made poor, those just men acknowledge themselves sinners, those lions be made dogs. “Let them be converted at evening, and suffer hunger as dogs. And they shall go around the city.” What city? That world, which in certain places the Scripture calls “the city of standing round:” that is, because in all nations everywhere the world had encompassed the one nation of Jews, where such words were being spoken, and it was called “the city of standing round.” Around this city shall go those men, now having become hungry dogs. In what manner shall they go around? By preaching. Saul out of a wolf was made a dog at evening, that is, being late converted by the crumbs of his Lord, in His grace he ran, and went around the city.
15. “Behold, themselves shall speak in their mouth, and a sword is on the lips of them”. Here is that sword twice whetted, whereof the Apostle says, “And the sword of the Spirit, which is the Word of God.” Wherefore twice whetted? Wherefore, but because smiting out of both Testaments? With this sword were slain those whereof it was said to Peter, “Slay, and eat.” “And a sword is on the lips of them. For who has heard?” They all speak in their mouth, “Who has heard?” That is, they shall be angry with men that are slow to believe. They that a little before were even themselves unwilling to believe, do feel disgust from men not believing. And truly, brethren, so it is. You see a man slow before he is made a Christian; you cry to him daily, hardly he is converted: suppose him to be converted, and then he would have all men to be Christians, and wonders that not yet they are. It has chanced out to him at evening to have been converted: but because he has been made hungering like a dog, he has also on his lips a sword; he says, “Who has heard?” What is, “Who has heard?” “Who has believed our hearing, and to whom has the arm of the Lord been revealed?” “For who has heard?” The Jews believe not: they have turned them to the nations, and have preached. The Jews did not believe; and nevertheless through believing Jews the Gospel went around the city, and they said, “For who has heard?” “And You, Lord, shall deride them”. All nations are to be Christian, and you say, “Who has heard?” What is, “shall deride them”? “As nothing You shall esteem all nations.” Nothing for You it shall be; because a most easy thing it will be for all nations to believe in You.
16. “My strength to You I will keep”. For those strong men have fallen for this reason; because their strength to You they have not kept: that is, they that upon me have risen up and rushed, on themselves have relied. But I “my strength to You will keep:” because if I withdraw, I fall; if I draw near, stronger I am made. For see, brethren, what there is in a human soul. It has not of itself light, has not of itself powers: but all that is fair in a soul, is virtue and wisdom: but it neither is wise for itself, nor strong for itself, nor itself is light to itself, nor itself is virtue to itself. There is a certain origin and fountain of virtue, there is a certain root of wisdom, there is a certain, so to speak, if this also must be said, region of unchangeable truth: from this the soul withdrawing is made dark, drawing near is made light. “Draw near to Him, and be made light:” because by withdrawing you are made dark. Therefore, “my strength, I will keep to You:” not from You will I withdraw, not on myself will I rely. “My strength, to You I will keep: because, O God, my lifter up You are.” For where was I, and where am I? Whence have You taken me up? What iniquities of mine have You remitted? Where was I lying? To what have I been raised up? I ought to have remembered these things: because in another Psalm is said, “For my father and my mother have forsaken me, but the Lord has taken me unto Him.”
17. “My God, the mercy of Him shall come before me”. Behold what is, “My strength, to You I will keep:” on myself I will in no ways at all rely. For what good thing have I brought, that you should have mercy on me, and should justify me? What in me have You found, save sins alone? Of Yours there is nothing else but the nature which Thou hast created: the other things are my own evil things which You have blotted out. I have not first risen up to You, but to awake me You have come: for “His mercy shall come before me.” Before that anything of good I shall do, “His mercy shall come before me.” What answer here shall the unhappy Pelagius make? “My God has shown to me among mine enemies”. How great mercy He has put forth concerning me, among mine enemies He has showed. Let one gathered compare himself with men forsaken, and one elect with men rejected: let the vessel of mercy compare itself with the vessels of wrath; and let it see how out of one lump God has made one vessel unto honour, another unto dishonour.
“For so God, willing to show wrath, and to manifest His power, has brought in, in much patience, the vessels of wrath, which have been perfected unto perdition.” And wherefore this? “In order that He might make known His riches upon the vessels of mercy.” If therefore vessels of wrath He has brought in, wherein He might make known His riches upon the vessels of mercy, most rightly has been said, “His mercy shall come before me: My God has showed to me among mine enemies:” that is however great mercy He has had concerning me, to me He has showed it among these men concerning whom He has not had mercy. For unless the debtor be in suspense, he is less grateful to him by whom the debt has been forgiven. “My God has showed to me among mine enemies.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)