Matthew 5:21-22
You have heard that it was said to those of old, You shall not murder, and whoever murders will be in danger of the judgment.’ But I say to you that whoever is angry with his brother without a cause shall be in danger of the judgment.

This was a new teaching.
The Law said you shall not murder. Ex 20:13
Jesus said sin is not only in action but also in thought. Unrighteous anger is as dangerous as murder.
He also tossed calling people names into the mix.
Perhaps I have never killed someone but I have thought really bad thoughts about them and called them horrible things.
In that sense, I am a murderer.
I thank God that He forgave me of this.
He also changed me so I don’t have to get angry or call people names.
He can change you too!