Matthew 5:28

But I say unto you, that everyone that looketh upon a woman to lust after her hath committed adultery with her already in his heart.

Thus, Christ made the lustful thought as sinful as the overt act. In the light of this, who is innocent? In this commandment, just as in the case of the Fifth Commandment, Jesus was more concerned with antecedents than with overt sins. Adultery proceeds from impure thinking; and in this passage Christ's law appears far higher and more discerning than the Decalogue.