Matthew 5:28
{5:28} But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.
This scripture should be written down in the long list of many others that is unfortunately misunderstood, and misinterpreted.
This wasn't a code or strict law Christ was creating. He was rather humbling, and implicating those who thought they were perfect by strict obedience to the Law. He's telling them basically "You think you got it all together, you think you are perfect. But I tell you, even if you've looked on another woman with lust in your heart you've sinned." I think Jesus knew this was a deal breaker for anyone. The message to the Pharisee was "YOU ARE A SINNER!" But his point wasn't to implicate into condemnation, but so they would realize the insufficiency of their own righteousness which was nothing more than filthy rags.