1....“The ungodly has said in himself that he will sin: there is no fear of God before his eyes”. Not of one man, but of a race of ungodly men he speaks, who fight against their own selves, by not understanding, that so they may live well; not because they cannot, but because they will not. For it is one thing, when one endeavours to understand some thing, and through infirmity of flesh cannot; as says the Scripture in a certain place, “For the corruptible body presses down the soul, and the earthly tabernacle weighs down the mind that muses upon many things;” but another when the human heart acts mischievously against itself, so that what it could understand, if it had but good will thereto, it understands not, not because it is difficult, but because the will is contrary. But so it is when men love their own sins, and hate God's Commandments. For the Word of God is your adversary, if you be a friend to your ungodliness; but if you are an adversary to your ungodliness, the Word of God is your friend, as well as the adversary of your ungodliness....
2. “For he has wrought deceitfully in His sight”. In whose sight? In His, whose fear was not before the eyes of him that did work deceitfully. “To find out his iniquity, and hate it.” He wrought so as not to find it. For there are men who as it were endeavour to seek out their iniquity, and fear to find it; because if they should find it, it is said to them, Depart from it: this you did before you knew; you did iniquity being in ignorance; God gives pardon: now you have discovered it, forsake it, that to your ignorance pardon may easily be given; and that with a clear face you may say to God, “Remember not the sins of my youth, and of my ignorance.” Thus he seeks it, thus he fears lest he find it; for he seeks it deceitfully. When says a man, I knew not that it was sin? When he has seen that it is sin, and ceases to do the sin, which he did only because he was ignorant: such an one in truth would know his sin, to find it out, and hate it. But now many “work deceitfully to find out their iniquity:” they work not from their heart to find it out and hate it. But because in the very search after iniquity, there is deceit, in the finding it there will be defence of it. For when one has found his iniquity, lo now it is manifest to him that it is iniquity. Do it not, you say. And he who wrought deceitfully to find it out, now he has found, hates it not; for what says he? How many do this! Who is there that does it not? And will God destroy them all? Or at least he says this: if God would not these things to be done, would men live who commit the same? Do you see that you worked deceitfully to find out your iniquity? For if not deceitfully but sincerely you had wrought, you would now have found it out, and hated it; now you have found it out, and you defend it; therefore you worked deceitfully, when you sought it.
3. “The words of his mouth are iniquity and deceit: he would not understand, that he might do good”. You see that he attributes that to the will: for there are men who would understand and cannot, and there are men who would not understand, and therefore understand not. “He would not understand, that he might do good.”
4. “He has meditated iniquity on his bed.” What said He, “On his bed?”. “The ungodly has said in himself, that he will sin:” what above he said, in himself, that here he said, “On his bed.” Our bed is our heart: there we suffer the tossing of an evil conscience; and there we rest when our conscience is good. Whoso loves the bed of his heart, let him do some good therein. There is our bed, where the Lord Jesus Christ commands us to pray. “Enter into your chamber, and shut your door.” What is, “Shut your door?” Expect not from God such things as are without, but such as are within; “and your Father which sees in secret, shall reward you openly.” Who is he that shuts not the door? He who asks much from God such things, and in such wise directs all his prayers, that he may receive the goods that are of this world. Your door is open, the multitude sees when you pray. What is it to shut your door? To ask that of God, which God alone knows how He gives. What is that for which you pray, when you have shut the door? What “eye has not seen, nor ear heard, or has entered into the heart of man.” And haply it has not entered into your very bed, that is, into your heart. But God knows what He will give: but when shall it be? When the Lord shall be revealed, when the Judge shall appear....
5. “He has set himself in every way that is not good.” What is, “he has set himself”? He has sinned perseveringly. Whence also of a certain pious and good man it is said, “He has not stood in the way of sinners.” As this “has not stood,” so that “has set himself.” “But wickedness has he not hated.” There is the end, there the fruit: if a man cannot but have wickedness, let him at least hate it. For when you hate it, it scarcely occurs to you to do any wickedness. For sin is in our mortal body, but what says the Apostle? “Let not sin reign in your mortal body, that you should obey it in the lusts thereof.” When begins it not to be therein? When that shall be fulfilled in us which he says, “When this corruptible shall have put on incorruption, and this mortal shall have put on immortality.” Before this come to pass, there is a delighting in sin in the body, but greater is the delighting and the pleasure in the Word of Wisdom, in the Commandment of God. Overcome sin and the lust thereof. Sin and iniquity do thou hate, that you may join yourself to God, who hates it as well as thou. Now being joined in mind unto the Law of God, in mind you serve the Law of God. And if in the flesh thou therefore servest the law of sin, because there are in you certain carnal delightings, then will there be none when you shall no longer fight. It is one thing not to fight, and to be in true and lasting peace; another to fight and overcome; another to fight and to be overcome; another not to fight at all, but to be carried away....
6. “Your mercy, O Lord, is in the heavens, and Your truth reaches even unto the clouds”. I know not what Mercy of Him he means, which is in the heavens. For the Mercy of the Lord is also in the earth. You have it written, “The earth is full of the Mercy of the Lord.” Of what Mercy then speaks He, when He says, “Your Mercy, O Lord, is in the heavens”? The gifts of God are partly temporal and earthly, partly eternal and heavenly. Whoso for this worships God, that he may receive those temporal and earthly goods, which are open to all, is still as it were like the brutes: he enjoys indeed the Mercy of God, but not that which is excepted, which shall not be given, save only to the righteous, to the holy, to the good. What are the gifts which abound to all? “He makes His sun to rise on the evil and on the good, and sends rain on the just and on the unjust.” Who has not this Mercy of God, first that he has being, that he is distinguished from the brutes, that he is a rational animal, so as to understand God; secondly, that he enjoys this light, this air, rain, fruits, diversity of seasons, and all the earthly comforts, health of body, the affection of friends, the safety of his family? All these are good, and they are God's gifts....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)