The great quote of rationality a la Socrates (or Plato, or Aristotle)

Help a brother out?

There’s a great quote by one of The Big 3 Greek Philosophers (EDIT: Reference to Cicero removed) which I can paraphrase by memory as:

“I consider it rather better for myself to be proven wrong than to prove someone else wrong, just as I’m better off being cured of a disease than curing someone of one.”

I can’t find the quote, or from which of the Three it is.

Anybody know? Or know where to look? I’ve already tried varying google search techniques and perused the Wikiquotes article on each of them.