22 “The trees of the plain shall be satisfied”: but with this grace, brought forth out of the earth. “The trees of the plain,” are the lower orders of the nations. “And the cedars of Libanus which He has planted.” The cedars of Libanus, the powerful in the world, shall themselves be filled. The bread, and wine, and oil of Christ has reached senators, nobles, kings; the trees of the plain are filled. First the humble are filled; next also the cedars of Libanus, yet those which He has planted; pious cedars, religious faithful; for such has He planted. For the ungodly also are cedars of Libanus; for, “The Lord shall break the cedars of Libanus.” For Libanus is a mountain: there are those trees, even according to the letter most long-lived and most excellent. But Libanus is interpreted, as we read in those who have written of these things, a brightness: and this brightness seems to belong to this world, which at present shines and is refulgent with its pomps. There are the cedars of Libanus, which the Lord has planted; those which the Lord has planted shall be filled....
23. “There shall the sparrows build their nests: their leader is the house of the coot”. Where shall the sparrows build? In the cedars of Libanus....Who are the sparrows? Sparrows are birds indeed, and fowls of the air, but small fowls are wont to be called sparrows. There are therefore some spiritual ones that build in the cedars of Libanus: that is, there are certain servants of God who hear in the Gospel, “Sell all that you have, and give to the poor; and you shall have treasure in heaven; and come and follow Me.”...Let him who has resigned many things, not be proud. We know that Peter was a fisherman: what then could he give up, to follow our Lord? Or his brother Andrew, or John and James the sons of Zebedee, themselves also fishermen; and yet what did they say? “Behold, we have forsaken all, and followed You.” Our Lord said not to him, You have forgotten your poverty; what have you resigned, that you should receive the whole world? He, my brethren, who resigned not only what he had, but also what he longed to have, resigned much....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)