The answer is: juxtaposition.
Juxtaposition is the contrast between two things which are seen or placed close together, so that the differences are pointed out. In "Hamlet," Polonious advises his son Laertes not to borrow or lend money - lending makes you lose your money and your friend, while borrowing makes people spend money in an irresponsible way.
Catharsis is the release of repressed emotions. Foreshadowing and dramatic irony are not correct either because there are no further money affairs in the play.