31 Perhaps by the heavens we here may understand, without being far-fetched, the righteous themselves, the saints of God, abiding in whom God has thundered in His commandments, lightened in His miracles, watered the earth with the wisdom of truth, for “The heavens have declared the glory of God.” But shall they perish? Shall they in any sense perish? In what sense? As a garment. What is, as a garment? As to the body. For the body is the garment of the soul; since our Lord called it a garment, when He said, “Is not the life more than meat, and the body than raiment?” How then does the garment perish? “Though our outward man perish, yet the inward man is renewed day by day.” They then shall perish: but as to the body: “But You shall endure.”...Such heavens therefore shall perish; not, however, for ever; they shall perish, that they may be changed. Does not the Psalm say this? Read the following: “They shall all wax old as does a garment; and as a vesture shall Thou change them, and they shall be changed.” You hear of the garment, of the vesture, and do you understand anything but the body? We may therefore hope for the change of our bodies also, but from Him who was before us, and abides after us....“But You are the same, and Your years shall not fail”. But what are we to those years with these beggarly years? And what are they? Yet we ought not to despair. He had already said in His great and exceeding Wisdom, “I Am That I Am;” and yet He says to console us, “I am the God of Abraham, and the God of Isaac, and the God of Jacob:” and we are Abraham's seed: even we, although abject, although dust and ashes, trust in Him. We are servants: but for our sakes our Lord took the garb of a servant: for us who are mortal the Immortal One deigned to die, for our sakes He showed His example of resurrection. Let us therefore hope that we may reach these lasting years, in which days are not spent in a revolution of the Sun, but what is abides even as it is, because it alone truly Is.
32. “The children of Your servants shall dwell there: and their seed shall stand fast for ages”: for the age of ages, the age of eternity, the age that abides. But, “the children,” he says, “of Your servants:” is it to be feared lest we be the servants of God, and our children, and not ourselves, dwell there? Or if we are the children of the servants, inasmuch as we are the Apostles' children, what are we to say? Can those children rising after have so unhappy a presumption, as to boast in their late succession, and so to venture to say, We shall be there; the Apostles will not be there? May this be far from their piety as children, from their faith as little ones, from their understanding when of age! The Apostles also will be there: rams go before, lambs follow. Wherefore then, “the children of Your servants;” and not in brief, “Your servants”? Both they are Your servants, and their children are Your servants; and the children of these, their grandsons, what are they but Your servants? You would include them all briefly, if You should say, Your servants shall dwell therein....“The children of Your servants,” are the works of Your servants; no one shall dwell there, but through his own works. What therefore means, Their children shall dwell? Let no man boast that he shall dwell there, if he calls himself God's servant, and has not works; for none but children shall dwell there. What means therefore, “The children of Your servants shall dwell there”? Your servants shall dwell there by their own works, Your servants shall dwell there through their own children. Be not therefore barren, if you dost wish to dwell there; send before the children whom you may follow, by sending them before you, not by burying them. Let your children lead you to the land of promise, the land of the living, not of the dying: while you are living here in this pilgrimage, let them go before you, let them receive you....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)