Four brisk lines of manners: come when you're called, do what you're bid, shut the door after you, and never sulk about it. Short enough to remember after a single read.
From Mother Goose / Nursery Rhymes (traditional). See the whole collection.
Come when you're called,
Do what you're bid,
Shut the door after you,
And never be chid.
About this rhyme
Text has four lines: three instructions plus a fourth consequence line ('never be chid'), consistent with the draft's 'four short lines... all three'.
Four short lines of plain house rules: come when called, do as you're asked, shut the door behind you. It reads like it was written by someone who had said all three more than once.
A fair one to recite at the door itself, not just at bedtime.
Public domain. Text from The Real Mother Goose (Blanche Fisher Wright, 1916), via Project Gutenberg. View the source edition