Пусть первым бросит камень, кто безгрешен

Before condemning anyone, ask yourself whether you are blameless. See Других не суди, на себя погляди (Д)

Cf: Cast not the first stone (Br.). Не that is without sin among you, let him cast the first stone (Br.). Не that is without sin among you, let him first cast a stone at her (Am., Br.). Let him that is without sin cast the first stone (Am.)