Phonetic: "Kol ha'po'sel be'mu'mo po'sel."

Translation: He who criticizes testifies to his own vice.

Meanings:

• When one is focusing, mentioning or criticizing someone else's vice, by doing so he is attesting to his own vice.
  
• Focusing on someone else's vice usually derives from our familiarity with that same vice - as being a part of us.
  
• Avoiding criticism will help us focus on our fellowmen's positive qualities instead of the negative ones. This will enable a better communication by creating a constructive and encouraging force, allowing for spiritual life of a higher level.