Sauce for the goose is sauce for the gander. With age comes wisdom. Out of the mouths of babes and sucklings come all wise sayings. Bear ye one another's burdens. For every man shall bear his own burden.
Fools think alike.
A rolling stone gathers no moss. A setting hen never lays. A hollow pot makes the most noise. The squeaky wheel gets the grease. Faint heart never won fair lady.