Laertes is Polonius' son and, early in the play, Polonius is concerned when Laertes leaves home to study in France. Thus Polonius offers Laertes these famous words of advice:
Neither a borrower nor a lender be;
For loan oft loses both itself and friend,
And borrowing dulls the edge of husbandry.
This above all: to thine ownself be true,
And it must follow, as the night the day,
Thou canst not then be false to any man. (1.3.59)