Ver.22: "But I say unto you, That whosoever is angry with His brother without good cause shall be liable to judgement. "
The prophets, about to prophesy, would say, "Thus saith the Lord," but Christ says, "I say", showing the authority of His divinity. For the prophets were servants; but He is the Son and possesses all that the Father has. He who "is angry with his brother without good cause" is condemned; but if anyone should get angry for good reason, either by way of chastisement or out of spiritual zeal, he is not condemned. For even Paul spoke words of anger to Elymas the Magician and to the high priest, not "without good cause", but out of zeal. But when we get angry over money or opinions, then it is "without good cause".
"And whosoever shall say to his brother, Raca, shall be liable to the council."
"The council" means the court of the Hebrews. "Raca" means something like "Hey, you!"as we say to someone whom we scorn, "Hey you, get out of here!". The Lord exhorts us in these matters because He desires to teach us to be strict even in small things and to give honor to one another. Some say that "Raca" is Syriac for "despicable" or "scum". Therefore, whoever insults his brother as "despicable" will be liable to the council of the holy apostles when they sit to judge the twelve tribes.
"But whosoever shall say, Thou fool, shall be liable to the gehenna of fire."
There are many who say and believe that this is too grievous and severe a judgement. But it is not. For is he who would deny the existence of his brothers faculties of reason and thought, those characteristics by which we differ from the beast, is such a man not deserving of gehenna? For he who reviles and insults, dissolves love; and when love is disolved, all the virtues are destroyed along with it, just as when love is present it unites all the virtues. Therefore, he who hurls insults, destroys all the virtues by tearing love to shreads, and rightly does he deserve the fire of hell.
Blessed Theophylact, The The Explanation of The Gospel According to St. Matthew