The holy Baal Shem Tov (Rebbe Yisroel ben Eliezer zt"l) taught that if you see another person doing an aveirah (transgression), you should look into yourself, because you likely have that flaw as well. How does this make sense? Different people have different flaws!
So, as it was written on Nikolsburg.org, “The same pertains to all of us,” explains the Baal Shem Tov. “Whatever you see in others is truly something you can find in yourself. If you notice sins in others, it is a reflection of your own deeds. If you would be clean and pure, you would see only beauty and purity in others.”
The Baal Shem Tov zt"l himself followed this teaching, as can be seen from the following story:
- Four Chassidic Masters, pages 20-21. By Rebbe Avraham J. Twerski M.D. shlita. A PocketScroll© book. A Shaar Press Publication©.