It is a royal privilege to do good and be ill spoken of.
ἀκούσας ποτὲ ὅτι Πλάτων αὐτὸν κακῶς λέγει, “βασιλικόν,” ἔφη, “καλῶς ποιοῦντα κακῶς ἀκούειν.”
Original text (Ancient Greek)
Notes from Wikiquote
§ 3; quoted also by Marcus Aurelius, vii. 36