4 You can see for yourself why I mention these things; without expressly saying it I am inviting you to take up your abode at the holy places. Your abundance has supported the want of many that some day their riches may abound to supply your want; you have made to yourself “friends of the mammon of unrighteousness that they may receive you into everlasting habitations.” Such conduct deserves praise and merits to be compared with the virtue of apostolic times. Then, as you know, believers sold their possessions and brought the prices of them and laid them down at the apostles' feet: a symbolic act designed to show that men must trample on covetousness. But the Lord yearns for believers' souls more than for their riches. We read in the Proverbs: “the ransom of a man's soul are his own riches.” We may, indeed, take a man's own riches to be those which do not come from some one else, or from plunder; according to the precept: “honour God with your just labours.” But the sense is better if we understand a man's “own riches” to be those hidden treasures which no thief can steal and no robber wrest from him.
Source: Letters (New Advent)