Give thy thoughts no tongue,
Nor any unproportion’d thought his act.
Be thou familiar, but by no means vulgar.
Those friends thou hast, and their adoption tried,
Grapple them unto thy soul with hoops of steel;
But do not dull thy palm with entertainment
Of each new-hatch’d, unfledg’d comrade. Beware
Of entrance to a quarrel; but, being in,
Bear’t that the opposed may beware of thee.
Give every man thy ear, but few thy voice:
Take each man’s censure, but reserve thy judgment.
Costly thy habit as thy purse can buy,
But not express’d in fancy; rich, not gaudy:
For the apparel oft proclaims the man;
And they in France of the best rank and station
Are most select and generous chief in that.
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 own self be true;
And it must follow, as the night the day,
Thou canst not then be false to any man.

– William Shakespeare

Hamlet, Act 1, Scene 3. This famous piece of fatherly advice is by Polonius to Laertes just before the latter leaves for France. Polonius is bidding his son farewell and giving him this rather long list of advice on how he should behave. It shows how much Polonius loves his son. But it also shows the hypocrisy of Polonius as a lot of the advice he dishes out, ironically he doesn’t follow it himself. A case of, do as I say, don’t do as I do.