1 The title of the Psalm is, “For her who receives the inheritance.” The Church then is signified, who receives for her inheritance eternal life through our Lord Jesus Christ; that she may possess God Himself, in cleaving to whom she may be blessed, according to that, “Blessed are the meek, for they shall possess the earth.” What earth, but that of which it is said, “You are my hope, my portion in the land of the living”? And again more clearly, “The Lord is the portion of mine inheritance and of my cup.” And conversely the word Church is said to be God's inheritance according to that, “Ask of Me, and I shall give you the heathen for your inheritance.” Therefore is God said to be our inheritance, because He feeds and sustains us: and we are said to be God's inheritance, because He orders and rules us. Wherefore it is the voice of the Church in this Psalm called to her inheritance, that she too may herself become the inheritance of the Lord.
2. “Hear my words, O Lord”. Being called she calls upon the Lord; that the same Lord being her helper, she may pass through the wickedness of this world, and attain unto Him. “Understand my cry.” The Psalmist well shows what this cry is; how from within, from the chamber of the heart, without the body's utterance, it reaches unto God: for the bodily voice is heard, but the spiritual is understood. Although this too may be God's hearing, not with carnal ear, but in the omnipresence of His Majesty.
3. “Attend to the voice of my supplication;” that is, to that voice, which he makes request that God would understand: of which what the nature is, he has already intimated, when he said, “Understand my cry. Attend to the voice of my supplication, my King, and my God”. Although both the Son is God, and the Father God, and the Father and the Son together One God; and if asked of the Holy Ghost, we must give no other answer than that He is God; and when the Father, and the Son, and the Holy Ghost are mentioned together, we must understand nothing else, than One God; nevertheless Scripture is wont to give the appellation of King to the Son. According then to that which is said, “By Me man comes to the Father,” rightly is it first, “my King;” and then, “my God.” And yet has not the Psalmist said, Attend You; but, “Attend.” For the Catholic faith preaches not two or three Gods, but the Very Trinity, One God. Not that the same Trinity can be together, now the Father, now the Son, now the Holy Ghost, as Sabellius believed: but that the Father must be none but the Father, and the Son none but the Son, and the Holy Ghost none but the Holy Ghost, and this Trinity but One God. Hence when the Apostle had said, “Of whom are all things, by whom are all things, in whom are all things,” he is believed to have conveyed an intimation of the Very Trinity; and yet he did not add, to Them be glory; but, “to Him be glory.”
4. “Because I will pray unto You. O Lord, in the morning You will hear my voice.” What does that, which he said above, “Hear Thou,” mean, as if he desired to be heard immediately? But now he says, “in the morning You will hear;” not, hear Thou: and, “I will pray unto You;” not, I do pray unto You: and, as follows, “in the morning I will stand by You, and will see;” not, I do stand by You, and do see. Unless perhaps his former prayer marks the invocation itself: but being in darkness amidst the storms of this world, he perceives that he does not see what he desires, and yet does not cease to hope, “For hope that is seen, is not hope.” Nevertheless, he understands why he does not see, because the night is not yet past, that is, the darkness which our sins have merited. He says therefore, “Because I will pray unto You, O Lord;” that is, because You are so mighty to whom I shall make my prayer, “in the morning You will hear my voice.” You are not He, he says, that can be seen by those, from whose eyes the night of sins is not yet withdrawn: when the night then of my error is past, and the darkness gone, which by my sins I have brought upon myself, then “You will hear my voice.” Why then did he say above not, “You will hear,” but “hear Thou”? Is it that after the Church cried out, “hear Thou,” and was not heard, she perceived what must needs pass away to enable her to be heard? Or is it that she was heard above, but does not yet understand that she was heard, because she does not yet see by whom she has been heard; and what she now says, “In the morning You will hear,” she would have thus taken, In the morning I shall understand that I have been heard? Such is that expression, “Arise, O Lord,” that is, make me arise. But this latter is taken of Christ's resurrection: but at all events that Scripture, “The Lord your God proves you, that He may know whether ye love Him,” cannot be taken in any other sense, than, that you by Him may know, and that it may be made evident to yourselves, what progress you have made in His love.
5. “In the morning I will stand by You, and will see”. What is, “I will stand,” but “I will not lie down”? Now what else is, to lie down, but to take rest on the earth, which is a seeking happiness in earthly pleasures? “I will stand by,” he says, “and will see.” We must not then cleave to things earthly, if we would see God, who is beheld by a clean heart. “For You are not a God who hast pleasure in iniquity. The malignant man shall not dwell near You, nor shall the unrighteous abide before Your eyes. You have hated all that work iniquity, You will destroy all that speak a lie. The man of blood, and the crafty man, the Lord will abominate”. Iniquity, malignity, lying, homicide, craft, and all the like, are the night of which we speak: on the passing away of which, the morning dawns, that God may be seen. He has unfolded the reason, then, why he will stand by in the morning, and see: “For,” he says, “You are not a God who hast pleasure in iniquity.” For if He were a God who had pleasure in iniquity, He could be seen even by the iniquitous, so that He would not be seen in the morning, that is, when the night of iniquity is over.
6. “The malignant man shall not dwell near You:” that is, he shall not so see, as to cleave to You. Hence follows, “Nor shall the unrighteous abide before Your eyes.” For their eyes, that is, their mind is beaten back by the light of truth, because of the darkness of their sins; by the habitual practice of which they are not able to sustain the brightness of right understanding. Therefore even they who see sometimes, that is, who understand the truth, are yet still unrighteous, they abide not therein through love of those things, which turn away from the truth. For they carry about with them their night, that is, not only the habit, but even the love, of sinning. But if this night shall pass away, that is, if they shall cease to sin, and this love and habit thereof be put to flight, the morning dawns, so that they not only understand, but also cleave to the truth.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)