At the time of Christ, the Jews were arguing about how best to please God.  Different parties had different ideas.  The Pharisees emphasized complete and literal obedience to the Law of Moses as it came down through the ages.  The Sadducees spiritualized the Law to a large degree and emphasized being good people.

Jesus paid little regard to their defenses.  For example, a lively issue was murder.  Jesus did not concentrate on murder but on anger.  But I tell you that anyone who is angry with a brother or sister will be subject to judgment.  5:22  

Another issue was adultery.  Jesus said, “You have heard that it was said, ‘You shall not commit adultery.’ But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.”  5:27, 28  Jesus was not interested in rules governing adultery but the root cause of adultery that left no one guiltless.

On divorce, the debate had to do with how to deal with divorce.  Jesus was quite clear.  Just do not do it!

On swearing oaths, he said, But I tell you, do not swear an oath at all.  All you need to say is simply ‘Yes’ or ‘No’; anything beyond this comes from the evil one.  5:34 – 37  Again, Jesus undercut all current argument by uncovering the evils of the heart.  He did not propose a new set of rules.

On rules of retribution, Jesus spoke, again, of a deeper truth. “You have heard that it was said, ‘Eye for eye, and tooth for tooth.’ But I tell you, do not resist an evil person. If anyone slaps you on the right cheek, turn to them the other cheek also.”  This sounds ridiculous for those who are not born again.  Human nature cries out, “revenge.”

The Jews debated who were their enemies and how should enemies be treated. Jesus said, “You have heard that it was said, ‘Love your neighbor and hate your enemy.’  But I tell you, love your enemies and pray for those who persecute you, that you may be children of your Father in heaven.”  5:43. 44  Love your enemies?  Now, what can be more impossible than that?

Jesus examined what was in the heart.  That is what matters, then and always.