In the Bible, particularly in the New Testament, Jesus speaks about the severity of anger and insults in the Sermon on the Mount. In Matthew 5:21-22, He says:
"You have heard that it was said to the people long ago, ‘You shall not murder, and anyone who murders will be subject to judgment.’ But I tell you that anyone who is angry with a brother or sister will be subject to judgment. Again, anyone who says to a brother or sister, ‘Raca,’ is answerable to the court. And anyone who says, ‘You fool!’ will be in danger of the fire of hell."
This passage emphasizes that while murder is a grave sin, harboring anger and insulting others is also serious and can have significant moral implications. It suggests that the attitudes and words we use towards others matter deeply in a spiritual sense. However, it doesn't equate insults directly with the act of killing in a legal or literal sense, but rather highlights the seriousness of our words and the emotional harm they can cause.