3 But if you have done so already, and have such money in your possession, and have filled your coffers thereby, and were heaping up treasure by these means: what you have comes of evil, now then add not evil to it, and make to yourselves friends of the mammon of iniquity. Had Zacchaeus what he had from good sources? Read and see. He was the chief of the publicans, that is, he was one to whom the public taxes were paid in: by this he had his wealth. He had oppressed many, had taken from many, and so had heaped much together.
Christ entered into his house, and salvation came upon his house; for so said the Lord Himself, “This day is salvation come to this house.” Now mark the method of this salvation. First he was longing to see the Lord, because he was little in stature: but when the crowd hindered him, he got up into a sycamore tree, and saw Him as He passed by. But Jesus saw him, and said, “Zacchaeus, come down, I must abide at your house.” You are hanging there, but I will not keep you in suspense.
I will not, that is, put you off. You wished to see Me as I passed by, today shall you find Me dwelling at your house. So the Lord went in unto him, and he, filled with joy, said, “The half of my goods I give to the poor.” Lo, how swiftly he runs, who runs to make friends of the mammon of iniquity. And lest he should be held guilty on any other account, he said, “If I have taken anything from any man, I” will “restore fourfold.” He inflicted sentence of condemnation on himself, that he might not incur damnation.
So then, you who have anything from evil sources, do good therewith. You who have not, wish not to acquire by evil means. Be good yourself, who does good with what is evilly acquired: and when with this evil you begin to do any good, do not remain evil yourself. Your money is being converted to good, and do you yourself continue evil?
Source: Sermons on Selected Lessons of the New Testament (New Advent)