źdźbło w oku bliźniego widzisz, a belki w swoim nie dostrzegasz

Etymology
lit. 'you see a blade of grass in the eye of your fellow man, and not see the beam (of wood) in your own', from the Bible, Matthew. 7:3-5.

Proverb

 * 1)  judge not, that ye be not judged, people who live in glass houses shouldn't throw stones