"Who are they, these people whose admiration you want to win? Aren't they the very people whom you're in the habit of describing as mad? What, do you want to be admired by madmen?" - Epictetus, Discourses 1.21.4
Via
The Practicing Stoic: A Philosophical User's Manual by Ward Farnsworth
I used the Oxford World's Classic edition translation which is linked above. Farnsworth uses another translation, which I'll offer here. It's mostly a matter of style, both say the same thing:
Who are these people whose admiration you seek? Aren't they the ones you are used to describing as mad, Well, then, is that what you want - to be admired by lunatics?
Epictetus is telling his students the same thing that Marcus Aurelius
was constantly reminding himself: not to worry about the opinion of others so long as you are doing the right thing. The Stoics emphasized, strongly emphasized, not looking outside yourself for external approval. Epictetus recognized our human tendency to worry or be upset about the opinion of people whose opinion we already know we shouldn't be worrying about but do anyway.*
*I picture Epictetus saying this to someone who is upset about having received negative comments on social media from strangers.