1 The title of this Psalm is brief and simple, and need not detain us; since we know whose resemblance David wore, and since in him we recognise ourselves also, for we too are members of that Body. The whole title is, “To David himself.” Let us see then, what is to David himself. The title of the Psalm is wont to tell us what is treated of within it: but in this, since the title informs us not of this, but tells us only to Whom it is chanted, the first verse tells us what is treated of in the whole Psalm, “I will confess to You.” This confession then let us hear. But first I remind you, that the term confession in Scripture, when we speak of confession to God, is used in two senses, of sin, and of praise. But confession of sin all know, confession of praise few attend to. So well known is confession of sin, that, wherever in Scripture we hear the words, “I will confess to You, O Lord,” or, “we will confess to You,” immediately, through habitually understanding in this way, our hands hurry to beating our breast: so entirely are men wont not to understand confession to be of anything, save of sin. But was then our Lord Jesus Christ Himself too a sinner, who says in the Gospel, “I confess to You, Father, Lord of heaven and earth”? He goes on to say what He confesses, that we might understand His confession to be of praise, not of sin, “I confess to You, Father, Lord of heaven and earth, because You have hid these things from the wise and prudent, and hast revealed them unto babes.” He praised the Father, he praised God, because He despises not the humble, but the proud. And such confession are we now going to hear, of praise of God, of thanksgiving. “With my whole heart.” My whole heart I lay upon the altar of Your praise, an whole burnt-offering of praise I offer to You....“I will confess to You, O Lord, with my whole heart: for You have heard the words of my mouth”. What mouth, save my heart? For there have we the voice which God hears, which ear of man knows not at all. We have then a mouth within, there do we ask, thence do we ask, and if we have prepared a lodging or an house for God, there do we speak, there are we heard. “For He is not far from every one of us, for in Him we live, and move, and have our being.” Nought makes you far off from God, save sin only. Cast down the middle wall of sin, and you are with Him whom you ask.
2. “And before the Angels will I sing unto You.” Not before men will I sing, but before the Angels. My song is my joy; but my joy in things below is before men, my joy in things above before the Angels. For the wicked knows not the joy of the just: “There is no joy, says my God, to the wicked.” The wicked rejoices in his tavern, the martyr in his chain. In what did that holy Crispina rejoice, whose festival is kept today? She rejoiced when she was being seized, when she was being carried before the judge, when she was being put into prison, when she was being brought forth bound, when she was being lifted up on the scaffold, when she was being heard, when she was being condemned: in all these things she rejoiced; and the wretches thought her wretched, when she was rejoicing before the Angels.
3. “I will worship toward Your holy Temple”. What holy Temple? That where we shall dwell, where we shall worship. For we hasten that we may adore. Our heart is pregnant and comes to the birth, and seeks where it may bring forth. What is the place where God is to be worshipped?...“The Temple of God is holy,” says the Apostle, “which Temple you are.” But assuredly, as is manifest, God dwells in the Angels. Therefore when our joy, being in spiritual things, not in earthly, takes up a song to God, to sing before the Angels, that very assembly of Angels is the Temple of God, we worship toward God's Temple. There is a Church below, there is a Church above also; the Church below, in all the faithful; the Church above, in all the Angels. But the God of Angels came down to the Church below, and Angels ministered to Him on earth, while He ministered to us; for, “I came not,” says He, “to be ministered unto, but to minister.”...The Lord of Angels died for man. Therefore, “I will worship toward Your holy Temple;” I mean, not the temple made with hands, but that which You have made for Yourself.
4. “And I will confess to Your Name in Your mercy and Your truth.”...These also which You have given to me, do I according to my power give to You in return: mercy, in aiding others; truth, in judging. By these God aids us, by these we win God's favour. Rightly, therefore, “All the ways of the Lord are mercy and truth.” No other ways are there whereby He can come to us, no other whereby we can come to Him. “For You have magnified Your holy Name over everything.” What sort of thanksgiving is this, brethren? He has magnified His holy Name over Abraham. Of Abraham was born Isaac; over that house God was magnified; then Jacob; God was magnified, who said, “I am the God of Abraham, and the God of Isaac, and the God of Jacob.” Then came his twelve sons. The name of the Lord was magnified over Israel. Then came the Virgin Mary. Then Christ our Lord, “dying for our sins, rising again for our justification,” filling the faithful with His Holy Spirit, sending forth men to proclaim throughout the Gentiles, “Repent ye,” etc. Behold, “He has magnified His holy Name above all things.”
5. “In what day soever I call upon You, do Thou quickly hear me”. Wherefore, “quickly”? Because You have said, “While yet you are speaking I will say, Lo, here I am.” Wherefore, “quickly”? Because now I seek not earthly happiness, I have learned holy longings from the New Testament. I seek not earth, nor earthly abundance, nor temporal health, nor the overthrow of my enemies, nor riches, nor rank: nought of these do I seek: therefore “quickly hear me.” Since You have taught me what to seek, grant what I seek....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)