Does anyone know where in the Politics Aristotle says that the ideal regime features citizens ruling in turns because it is through being ruled well that we learn how to rule well?

I have gone through some of the major passages where he discusses ruling in turns (book 7, chapter 14, for instance), but I can't seem to find this particular argument. I wouldn't be surprised if it is no more than a single sentence in the text. I am interested in looking at the justifications for ruling in turns, and I can remember there being a justification besides the one that ruling in turns is consistent with the equality between citizens.

Even learning the book number would be helpful, because I might just have to quickly skim the entire Politics.