Harmony begins in the heart, not in the law.

20For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven.
21"You have heard that it was said to the people long ago, 'Do not murder, and anyone who murders will be subject to judgment.' 22But I tell you that anyone who is angry with his brother will be subject to judgment. Again, anyone who says to his brother, 'Raca,' is answerable to the Sanhedrin. But anyone who says, 'You fool!' will be in danger of the fire of hell.
23"Therefore, if you are offering your gift at the altar and there remember that your brother has something against you, 24leave your gift there in front of the altar. First go and be reconciled to your brother; then come and offer your gift.
25"Settle matters quickly with your adversary who is taking you to court. Do it while you are still with him on the way, or he may hand you over to the judge, and the judge may hand you over to the officer, and you may be thrown into prison. 26I tell you the truth, you will not get out until you have paid the last penny. (Matthew 5:20-26)

What does it really mean to be righteous? Is righteousness merely a legal reality? Is it all about either following or not following certain rules? That is not what Jesus is telling his listeners. Jesus is trying to make the point that true righteousness goes far deeper than just following certain rules.
The problem with the legal view is that it tempts one to think of their relationship with God as if it were a contract. You do your part of the bargain and God will do his part. It tempts you to think of your life only in terms of the minimum you need to do to keep on the right side of God, or even to see what you can get away with and still not be violating the contract, so that God is obligated to keep his part. Jesus is trying to tell his listeners that true righteousness goes far beyond the legal understanding of the law. Jesus is trying to get his listeners to understand the "heart" of the law.
Jesus reminds his listeners that it is wrong to commit murder. However, Jesus is telling them the deeper meaning of this commandment. God's intention was not just that people not actually murder each other. You have not necessarily fulfilled this commandment when you have managed to not physically kill another person. Jesus goes further in his instruction to his listeners. He tells them that to be angry with another person, to demean them by insults, in other words, to kill the heart of a person, is no different in the eyes of God than if one were to kill the body.
Jesus is asking them to consider the truth that the seeds of murder begin far earlier than the final act. Doesn't murder begin, Jesus is asking, way back in the angry word or the thoughtless insult? Isn't there a real death that occurs whenever we speak unkindly to others? There is discord, dissolution and pain in the relationship that wasn¹t there before and that we cannot take away. It has been brought into reality by our speaking. The words can be worked around and apologized for, but they cannot be unsaid. Damage to the relationship has been done. Killing the relationship is just as bad as killing the body.
Jesus is trying to teach his listeners the true meaning of God's commandment. Righteousness is not about just following the bare minimum of the law. The meaning of true righteousness is about maintaining right relationships. Right relationships do not start with the law, they start with the heart and with the soul.
This puts a whole new understanding to this commandment. When you hear the phrase "words can kill", it reminds us that what we say to one another is just as important as what we do to one another. To understand this message of Jesus, we have to learn to speak carefully. We must think before we speak words to one another that bring about death. It also forces us to understand the importance that God puts on relationships. We are to live in peace with one another. God's peace not just in the physical sense, but peace in the spiritual sense. Harmony begins in the heart, not in the law.

Peace and love,

Sue

"Then Jesus said to them all: "If anyone would come after me, he must deny himself and take up his cross daily and follow me". (Luke 9:23)