make money from another

As soon as Rabbi Levy entered his office, there was Arnold waiting for him.
"I need your advice, Rabbi," says Arnold.
"OK Arnold, how can I help, what’s bothering you?" asks Rabbi Levy
"Rabbi," asks Arnold, "is it right for one man to make money from another
man's errors?"
"No Arnold, it certainly isn’t," replies Rabbi Levy.
"Are you absolutely sure about that?" asks Arnold.
"About that, Arnold, I’m absolutely positive," replies Rabbi Levy.
"I’m so pleased to hear you say this, Rabbi," says Arnold, "so could you
please return the £300 I gave you to marry me to my wife Sadie?"