Enchiridion 50

Whatever principles are set before you, stand fast by these like laws, feeling that it would be impiety for you to transgress them. But pay no attention to what somebody says about you, for this is, at length, not under your control.

Epictetus, Enchiridion 50, translated by W. A. Oldfather

Whatever things (rules) are proposed to you [for the conduct of life] abide by them, as if they were laws, as if you would be guilty of impiety if you transgressed any of them. And whatever any man shall say about you, do not attend to it: for this is no affair of yours.

Epictetus, Enchiridion 50, translated by George Long

Whatever principles you put before you, hold fast to them as laws which it will be impious to transgress. But pay no heed to what any one says of you; for this is something beyond your own control.

Epictetus, Enchiridion 50, translated by P. E. Matheson