In chapter six Epictetus moves on to insist that we should only take pride in things that are that are our own. We shouldn't brag about owing a beautiful horse because the horse's beauty is it's own. The only thing that is ours is the wise use of our mental faculties. If we make good judgments and pursue virtue then Epictetus says we can go ahead and indulge our pride.
This is an interesting chapter because according to the stoic authors that I have read we should expect that we will not reach such a level that we could indulge our pride. I believe that Epictetus instead is trying to get us to focus on what is truly important. We must keep focused on virtue in all that we do. On a daily basis we need to remind ourselves of what is in our control and renounce all that is outside of our control. If we do so then we will be free because we will only desire the things are in our control.
But so often we get focused on external things. Not many of us today take pride in our horse, but we take pride in our cars, houses, clothes, etc. Epictetus reminds us that external things are not in our control, therefore we should not take pride in external things. This provides us with a good test of where our focus lies. If we find ourselves bragging or taking prideful joy in something then we need to re-orientate ourselves to virtue.