9] And I tell you, make friends for yourselves by means of unrighteous mammon, so that when it fails they may receive you into the eternal habitations. RSV-CE
I tell you, make friends for yourselves with dishonest wealth, 6 so that when it fails, you will be welcomed into eternal dwellings. NAB
6  Dishonest wealth: literally, “mammon of iniquity.” Mammon is the Greek transliteration of a Hebrew or Aramaic word that is usually explained as meaning “that in which one trusts.” The characterization of this wealth as dishonest expresses a tendency of wealth to lead one to dishonesty. Eternal dwellings: or, “eternal tents,” i.e., heaven. his opposed to the teachings.
9 And I say to you: Make unto you friends of the mammon of iniquity; that when you shall fail, they may receive you into everlasting dwellings Douay Rheims
Douay Rheims footnote:
9 “Mammon of iniquity”… Mammon signifies riches. They are here called the mammon of iniquity, because oftentimes ill gotten, ill bestowed, or an occasion of evil; and at the best are but worldly, and false; and not the true riches of a Christian.
9 “They may receive”… By this we see, that the poor servants of God, whom we have relieved by our alms, may hereafter, by their intercession, bring our souls to heaven.
Ver. 9. Make for yourselves friends, &c. Not that we are authorized to wrong our neighbour, to give to the poor: evil is never to be done, that good may come from it. (St. Thomas Aquinas) — But we are exhorted to make the poor our friends before God, by relieving them with the riches which justly indeed belong to us, but are called the mammon of iniquity, because only the iniquitous man esteems them as riches, on which he sets his affections; whilst the riches of the virtuous are wholly celestial and spiritual. (St. Augustine, de quæst. Evang.) — Of the mammon of iniquity. Mammon is a Syriac word for riches; and so it might be translated, of the riches of iniquity. Riches are called unjust, and riches of iniquity, not of themselves, but because they are many times the occasion of unjust dealings, and of all kind of vices. (Witham) — Mammon signifies riches. They are here called the mammon of iniquity, because oftentimes ill-gotten, ill-bestowed, or an occasion of evil; and at the best are but worldly, and false: and not the true riches of a Christian. — They may receive. By this we see, that the poor servants of God, whom we have relieved by our alms, may hereafter, by their intercession, bring our souls to heaven. (Challoner) — They may receive you into their eternal tabernacles. What a beautiful thought this! What a consolation to the rich man, when the term of his mortal existence is approaching, to think he shall have as many advocates to plead for his admittance into the eternal mansions of rest, as he has made friends among the poor by relieving their temporal wants. The rich give to the poor earthly treasures, the latter return in recompense eternal and infinite happiness. Hence we must infer, that the advantage is all on the side of the giver; according to the saying of our Lord, happier is the condition of him who gives, than of him who receives. (Haydock)
So…I haven’t seen a good explaination of what “make friends for yourselves by means of unrighteous mammon”…
Does anyone actually know what this means?