neither a borrower not a lender be

Neither a borrower not a lender be is a quote by Polonius in the Shakespeare play Hamlet during Act 1, scene 3 and lines 75-77. What the line means is that lending money to friends can be very risky since hitching debt onto personal relationships can cause a lot of resentment and if they dont pay you back in time or in full when you expect it, where the lender, the money and the friend lose the mutual friendship.