A while back I ran into a fanfic based on Dune. The fic wasn't memorable or worthwhile, but it contained a line which stuck in my memory: "Atreides always pay their debts"
It sounded like something from actual Dune canon, but it's been years since I read the books, so I don't recall for sure. Is my impression (that this line is somehow canon based) accurate? If so, where does the idea appear?