“You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lust has already committed adultery with her in his heart. If your right eye causes you to sin, tear it out and throw it away; it is better for you to lose one of your members than for your whole body to be thrown into hell. And if your right hand causes you to sin, cut it off and throw it away; it is better for you to lose one of your members than for your whole body to go into hell.
“It was also said, ‘Whoever divorces his wife, let him give her a certificate of divorce.’ But I say to you that anyone who divorces his wife, except on the ground of unchastity, causes her to commit adultery; and whoever marries a divorced woman commits adultery.
Matthew 5:27-32 (NRSV)