12 “The imprudent and unwise shall perish together.” Who is “the imprudent”? He that looks not out for himself for the future. Who is “the unwise”? He that perceives not in what evil case he is. But do thou perceive in what evil case you are now, and look out that thou be in a good case for the future. By perceiving in what evil case you are, you will not be unwise: by looking out for yourself for the future, you will not be imprudent. Who is he that looks out for himself?
That servant to whom his master gave what he should expend, and afterwards said to him, “You can not be my steward, give an account of your stewardship;” and who answered, “What shall I do? I cannot dig, to beg I am ashamed;” had, nevertheless, by even his master's goods made to himself friends, who might receive him when he was put out of his stewardship. Now he cheated his master in order that he might get to himself friends to receive him: fear not lest you be cheating, the Lord Himself exhorts you to do so: He says Himself to you, “Make to yourself friends of the mammon of unrighteousness.” Perhaps what you have got, you have gotten of unrighteousness: or perhaps this very thing is unrighteousness, that you have and another has not, you abound and another needs.
Of this mammon of unrighteousness, of these riches which the unrighteous call riches, make to yourself friends, and you shall be prudent: you are gaining for yourself, and art not cheating. For now you seem to lose it. Will you lose it if you place it in a treasury? For boys, my brethren, no sooner find some money, wherewith to buy something, than they put it in a money-box, which they open not until afterwards: do they, because they see not what they have got, on that account lose it?
Fear not: boys put in a money-box, and are secure: do you place it in the hand of Christ, and fear? Be prudent, and provide for yourself against the future in Heaven. Be therefore prudent, copy the ant, as says the Scripture: “Store in summer, lest you hunger in winter;” the winter is the last day, the day of tribulation; the winter is the day of offenses and of bitterness: gather what may be there for you for the future: but if you do not so, you will perish both imprudent and unwise.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)