35 Let us therefore see whether God fulfils His promises. After these stern penalties which have been recorded as having been inflicted upon this people and kingdom, that God might not be supposed to have fulfilled His promises in it, and so not to grant another kingdom in Christ, of which kingdom there shall be no end; the Prophet addresses Him in these words, “Lord, how long will You hide Yourself unto the end?”. For possibly it was not from them and to the end; because “blindness in part is happened to Israel, until the fullness of the Gentiles be come in, and so all Israel shall be saved.” But in the mean while “shall Your wrath burn like fire.”
36. “O remember what my substance is”. That David, who was placed among the Jews in the flesh, in Christ in hope, speaks “Remember what is my substance.” For not because the Jews fell away, did my substance fail: for from that people came the Virgin Mary, and from her the flesh of Christ; that Flesh sins not, but purifies sins; there, says David, is my substance. “O remember what my substance is.” For the root has not entirely perished; the seed shall come to whom the promise was made, ordained by Angels in the hand of a Mediator. “For You have not made all the sons of men for nought”. Lo! All the sons of men have gone into vanity: yet You have not made them for nought. If then all went into vanity, whom You have not made for nought; have You not reserved some instrument to purify them from vanity? This which You have reserved to Yourself to cleanse men from vanity is Your Holy One, in Him is my substance: for from Him are all, whom You have not made for nought, purified from their own vanity. To them it is said, “O you sons of men, how long are you heavy in heart? Wherefore have ye such pleasure in vanity, and seek after leasing?” Perhaps they might become anxious, and turn from their vanity, and when they found themselves polluted with it, might seek for purification from it: then help them, make them secure. “Know this also, that the Lord has made wonderful His Holy One.” He has made His Holy One to be admired: thence He has purified all from their vanity: there, says David, is my substance: O remember it! “For You have not made all the sons of men for nought.” You have therefore reserved something to purify them: and who is He whom You have reserved? “What man is he that lives, and shall not see death?” This man then who shall live and not see death, shall purify them from nothingness. For He made not all men for nought, nor can He who made them so despise His own creatures, as not to convert and purify them.
37. “What man is he that shall live, and shall not see death?”. For being raised from the dead He dies no more, and death has no more dominion over Him. And as in another Psalm it is said, “You shall not leave my soul in Hell, neither shall Thou suffer Your Holy One to see corruption,” the Apostolic teaching takes up this testimony, and in the Acts of the Apostles thus argues against the unbelieving; Men and brethren, we know that the patriarch David is dead and buried, and his flesh has seen corruption. Therefore it cannot be said of him, “neither shall Thou suffer Your Holy One to see corruption.” Of whom then is it said? “What man is he that shall live, and shall not see death?” Perhaps there is no man such. Nay, but “who is it?” is said to make you inquire, not despair. But perhaps there may be some man “that shall live, and shall not see death,” and yet perhaps he did not speak of Christ, who died? There is no man “that shall live, and shall not see death,” except Him who died for mortals. That you may be assured that it is said of Him, consider the sequel; “What man is he that lives, and shall not see death?” Did He never die then? He did. How then shall He live, and never see death? “He shall deliver His own soul from the hands of Hell.” He is spoken of alone indeed, in that He alone of all others “shall live, and shall not see death: He shall deliver His own soul from the hand of Hell,” because although the rest of His faithful shall rise from the dead, and shall themselves live for evermore, without seeing death; yet they shall not themselves deliver their own souls from the hands of Hell. He who delivers His own soul from the hands of Hell, Himself delivers those of His believers: they cannot do so of themselves. Prove that He delivers His own soul. “I have power to lay down My life, and I have power to take it again. No man takes 'it from Me;' for I Myself slept, but I lay it down of Myself, and take it again,” because it is He Himself who delivers His own soul from the hands of Hell.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)