2 The title then is not simply “To the sons of Korah,” but, “For understanding, to the sons of Korah.” This is the case also with that Psalm, the first verse of which the Lord Himself uttered on the Cross: “My God, My God, look upon Me; why have You forsaken Me?” For “transferring us in a figure” to what He was saying, and to His own Body (for we are also “His Body,” and He is our “Head”), He uttered from the Cross not His own cry, but ours. For God never “forsook” Him: nor did He Himself ever depart from the Father; but it was in behalf of us that He spoke this: “My God, My God, why have you forsaken Me?” For there follows, “Far from My health are the words of My offenses:” and it shows in whose person He said this; for sin could not be found in Him....
3. “O God, we have heard with our ears; our fathers have told us the work that You did in their days, and in the days of old”. Wondering wherefore, in these days, He has seemingly forsaken those whom it was His will to exercise in sufferings, they recall the past events which they have heard of from their fathers; as if they said, It is not of these things that we suffer, that our fathers told us! For in that other Psalm also, He said this, “Our fathers trusted in You; they trusted, and Thou delivered them. But I am a worm and no man; a reproach of men, and the outcast of the people.” They trusted, and Thou delivered them; have I then hoped, and have You forsaken me? And have I believed upon You in vain? And is it in vain that my name has been written in Your Book, and Your name has been inscribed on me? What our fathers told us was this:
“Your hand destroyed the nations; and You planted them: Thou weakened the peoples, and cast them out”. That is to say: “You drove out 'the peoples' from their own land, that You might bring 'them' in, and plant them; and might by Your mercy establish their kingdom.” These are the things that we heard from our fathers. But perhaps it was because they were brave, were men of battle, were invincible, were well-disciplined, and warlike, that they could do these things. Far from it. This is not what our fathers told us; this is not what is contained in Scripture. But what does it say, but what follows?
“For they gat not the land in possession by their own sword, neither did their own arm save them; but Your right hand, and Your arm, and the light of Your countenance”. Your “right hand” is Your Power: Your “arm” is Your Son Himself. And “the light of Your countenance.” What means this, but that You were present with them, in miracles of such a sort that Your presence was perceived. For when God's presence with us appears by any miracle, do we see His face with our own eyes? No. It is by the effect of the miracle He intimates to man His presence. In fact, what do all persons say, who express wonder at facts of this description? “I saw God present.” “But Your right hand, and Your arm, and the light of Your countenance; because You pleased in them:” i.e. so dealt with them, that You were well-pleasing in them: that whoso considered how they were being dealt with, might say, that “God is with them of a truth;” and it is God that moves them.
4. “What? Was He then other than now He is?” Away with the supposition. For what follows?
“You are Yourself my King and my God.”. “You are Yourself;” for You are not changed. I see that the times are changed; but the Creator of times is unchanged. “You are Yourself my King and my God.” You are wont to guide me: to govern me, to save me. “You who commandest salvation unto Jacob.” What is, “You who commandest”? Even though in Your own proper Substance and Nature, in which You are whatsoever You are, You were hid from them; and though You did not converse with the fathers in that which You are in Yourself, so that they could see You “face to face,” yet by any created being whatsoever “You command salvation unto Israel.” For that sight of You “face to face” is reserved for those set free in the Resurrection. And the very “fathers” of the New Testament too, although they saw Your mysteries revealed, although they preached the secret things so revealed to them, nevertheless said that they themselves saw but “in a glass, darkly,” but that “seeing face to face” is reserved to a future time, when what the Apostle himself speaks of shall have come. “When Christ our life shall appear, then shall you also appear with Him in glory.” It is against that time then that vision “face to face” is reserved for you, of which John also speaks: “Beloved, we are now the sons of God: and it does not yet appear what we shall be. We know that, when He shall appear, we shall be like Him; for we shall see Him as He is.” Although then at that time our fathers saw You not as You are, “face to face,” although that vision is reserved against the resurrection, yet, even though they were Angels who presented themselves, it is Thou, “Who commandest salvation unto Jacob.” You are not only present by Your own Self; but by whatsoever created being You appeared, it is Thou that dost “command” by them, that which You do by Your own Self in order to the salvation of Your servants: but that which they do whom Thou “commandest” it, is done to procure the salvation of Your servants. Since then You are Yourself “my King and my God, and You command salvation unto Jacob,” wherefore are we suffering these things?
Source: The Enarrations, or Expositions, on the Psalms (New Advent)