Proper Revenge

If you wish to take the proper revenge on your enemies you should increase your good qualities and conduct yourself in a straightforward fashion. In this way, your revenge on your enemies will take place by itself, for your elevated qualities will cause your enemy distress and he will mourn when he hears your good reputation. However, if you take revenge by perpetrating ugly deeds then your enemy will rejoice over your degradation and your disgrace and he will thus have had revenge upon you.

(Kitzur Shulchan Aruch 30:8)