Matthew 5:21-22

You have knowledge that it was said in old times, You may not put to death; and, Whoever puts to death will be in danger of being judged: But I say to you that everyone who is angry with his brother will be in danger of being judged; and he who says to his brother, Raca, will be in danger from the Sanhedrin; and whoever says, You foolish one, will be in danger of the hell of fire.