cast/throw the first stone, to

To be quick to attack someone or some- thing. The term comes from Jesus’ defense of an adulteress against vindictive Pharisees and scribes, who quoted the law of Moses and said she must be stoned. Jesus told them, “He that is without sin among you, let him first cast a stone at her” (Gospel of St. John, 8:7). The implication that the attacker is equally vulnerable was continued in the modern-day cliché, and spelled out even more in the old proverb, PEOPLE WHO LIVE IN GLASS HOUSES SHOULD NOT THROW STONES.