Matthew 5:22 (Luther)

Matthew 5:22. But I say to you that everyone who is angry with his brother shall be liable to judgment; whoever says to his brother, “Raca!” shall be liable to the council, and whoever says, “You fool!” shall be liable to the hell of fire.

See, this is the true light. It shows the real meaning of this commandment, and it makes their miserable gloss look shameful, like a dark lantern in contrast with the brightness of the sun. Now it shines so differently that they are astonished and say (Matt. 7:29): “That is teaching with authority,” not as their scribes. His exposition is clear enough and has often been discussed elsewhere. Still on account of the text, we have to emphasize the words a little. He says first: “Everyone who is angry with his brother shall be liable to judgment”; that is, he deserves the same punishment that is inflicted upon a murderer, namely, the sentence of death. He repeats the very words of the text He has just quoted (Lev. 24:17): “He who kills a man shall be put to death.” Now since a man who is angry with his brother comes under the same sentence, he also deserves the name “murderer.” By the second and third clauses, “whoever says to his brother, ‘Raca!’ or ‘You fool!’ is liable to the council and to the hell of fire,” He means the same as “liable to judgment,” namely, that such a person is liable to execution.
He mentions three items to show that the punishment becomes greater and more stringent as the sin progresses and breaks out further. He is using the language of the courtroom when a criminal is supposed to be punished. For example, if a man has committed murder, he is first liable to the judgment; that is, he is hauled up before the court, indicted, and a charge of murder is placed against him. This is the first level, or step, toward death; but the sentence has not yet been passed, and he still has a chance to defend himself and get off. But when, in the second step, the sentence of death has been passed upon him, then he is liable to the council. Then people take counsel about him to decide the punishment he is to receive; this means that he is even closer to death and cannot escape. When, in the third step, the sentence of death has been passed and everything has been decided, he is handed over to the executioner, who takes him away and performs his official function. With these three steps He shows how a man sinks deeper and deeper into punishment, just as a man who has been sentenced to be executed draws closer and closer to death. Thus it is as if He had said: “Whoever is angry in his heart, already deserves death before God. But whoever goes further and says, ‘Raca!’ or, ‘You fool!’ has already had his sentence pronounced upon him.” In other words, whoever is angry with his brother is already damned to the hell of fire. But whoever says, “Raca!” deserves to go still deeper into hell; and deeper yet, whoever kills with his words and fists as well. So there is only one punishment and damnation; but this becomes more stringent and severe, in accordance with the level and the virulence of the sin.
“Raca” is usually taken to represent the many ways in which we can show anger against our neighbor—when we refuse to talk to him or to look at him, when we laugh up our sleeve over his bad luck, or when in some other way we show that his complete ruination would make us happy. There are many of these poisonous and malicious worms who are bitterly and treacherously attacking us now, both in public and in secret. There is nothing that would make them as happy as hearing that we had all been exterminated. Yet they pose as holy Christian people!
The other term, “You fool!” means not only the attitudes we have been mentioning, but also all of the words that come out of a malicious and poisonous heart which is hostile to its neighbor. Otherwise, if they come out of a kindly and motherly heart, that is not a sin. Then it is permissible to scold and rebuke with words, as St. Paul calls his Galatians “foolish” (Gal. 3:1) and Christ says to His disciples (Luke 24:25): “O foolish men and slow of heart to believe.” What is more, we also have to get angry and put on a stern and unfriendly face. All this is a godly anger and vexation. It is directed at the wrong and not at the person, and it is intended to help our neighbor. In other words, such anger is necessary and indispensable in any house, in any position in life28 or in government, indeed, in any pulpit. If father and mother, judge, and preacher held back their mouths and their fists and did nothing to curb or punish evil, the wickedness of the world would destroy the government and the church and everything. So the command here is to “hate the deed, but love the doer,” as the lawyers say—if they only made the right use of it.29
Luther, M. (1999, c1956). Vol. 21: Luther's works, vol. 21 : The Sermon on the Mount and the Magnificat (J. J. Pelikan, H. C. Oswald & H. T. Lehmann, Ed.). Luther's Works (21:77). Saint Louis: Concordia Publishing House.