5 “A sojourner I will be in Your tabernacle even unto ages”. You see how he, of whom we have spoken, is he that cries. Which of us is a sojourner even unto ages? For a few days here we live, and we pass away: for sojourners here we are, inhabitants in Heaven we shall be. You are a sojourner in that place where you are to hear the voice of the Lord your God, “Remove.” For from that Home everlasting in the Heavens no one will bid you to remove. Here therefore a sojourner you are.
Whence also is said in another Psalm, “A sojourner I am with You and a stranger, as all my fathers were.” Here therefore sojourners we are; there the Lord shall give to us mansions everlasting: “Many are,” He says, “the mansions in My Father's house.” Those mansions not as though to sojourners He will give, but as though to citizens to abide for everlasting. Here however, brethren, because for no small time the Church was to be on this earth, but because here shall be the Church even unto the end of the world: therefore here He has said, “A dweller I will be in Your tabernacle even unto ages.”...Well, of a few days you would choose that the temptations should be: but how would She gather together all Her sons, unless for a long time She were to be here, unless even unto the end She were to be prolonged?
Do not envy the rest of mankind that hereafter shall be: do not, because you have already passed over, wish to cut down the bridge of mercy: be it here even for ever. And what of temptations, which needs must abound, by how much the more offenses come? For Himself says, “Because iniquity has abounded, the love of many shall wax cold.” But that Church, which cries from the ends of the earth, is in these circumstances whereof he speaks in continuation. “But he that shall have persevered even unto the end, the same shall be saved.”
But whence shall you persevere?...“I shall be covered up in the veiling of Your wings.” Behold the reason why we are in safety amid so great temptations, until there come the end of the world, and ages everlasting receive us; namely, because we are covered up in the veiling of His Wings. There is heat in the world, but there is a great shade under the wings of God.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)