cast the first stone

cast the first stone - первым бросить камень (скорополительно обвинять) (lit.)

Meaning: to be the first to blame someone, act self-righteously
When Christ was asked if an adulterous woman should be stoned in accordance with Mosaic law he replied, 'He that is without sin among you, let him first cast a stone at her' (John, 8:7), at which the crowd of accusers melted away