In Matthew 5:21-48, some people think that Jesus is comparing and contrasting the Old Law with his New Law. They see these passages as Jesus showing the Old Law to be about the external actions and the New Law to be about the heart. Jesus is actually calling the attention of his listeners to the fact that God has always cared about the hearts of his people. The scribes and the Pharisees had elevated their traditions to the same level (and in some cases to a higher level) as God's commands and teachings in the Old Testament.
by Greg Surles