Full Idea
Ariston says that rules are useless if you are virtuous, and useless if you are not.
Gist of Idea
Ariston says rules are useless for the virtuous and the non-virtuous
Source
report of Ariston (fragments/reports [c.250 BCE]) by Julia Annas - The Morality of Happiness 2.4
Book Reference
Annas,Julia: 'The Morality of Happiness' [OUP 1995], p.100