Testing Jesus, a group of scribes present Him with a woman caught in the act of adultery, the law requiring her to be stoned to death. Jesus asks that one free of sin casts the first stone, leaving him alone with the woman as the accusers recognize their own sins and depart.
"Jesus..came again into the temple, and all the people came unto him; and he sat down, and taught them. And the scribes and Pharisees brought unto him a woman taken in adultery..They say unto him, Master, this woman was taken in adultery, in the very act. Now Moses in the law commanded us, that such should be stoned: but what sayest thou? This they said, tempting him, that they might have to accuse him. But Jesus..said unto them, He that is without sin among you, let him first cast a stone at her..And they which heard it, being convicted by their own conscience, went out one by one.. and Jesus was left alone, and the woman standing in the midst. When Jesus had lifted up himself, and saw none but the woman, he said unto her, Woman, where are those thine accusers? hath no man condemned thee? She said, No man, Lord. And Jesus said unto her, Neither do I condemn thee: go, and sin no more."
excerpted from John 8:1-11
The idea of self-examination before accusing others is repeated by Jesus in Matthew 7:5, "Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother's eye."
glass house stones