“But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire.” (Matthew 5:22, KJV)
The word, “εικη”, translated as “without a cause” in the KJV is omitted in modern translations. The KJV reading is supported by the majority of manuscripts, being found in Aleph (second correction), D, L, W, Theta, 0233, 33, the majority of Byzantine manuscripts and other authorities (Nestle-Aland: Novum Testamentum Graece, 27th ed.). The earliest of these is W from the 4th/5th century. The omission is a minority reading, but is supported by three manuscripts that are earlier than W. These are: P64 (3rd century), Aleph (4th century) and B (4th century). However, the KJV reading is supported by Cyprian and Origen who lived in the 3rd century. Cyprian wrote:
“In Solomon in the Proverbs: Better is a patient man than a strong man; for he who restrains his anger is better than he who takes a city. Also in the same place: The imprudent man declares his anger on the same day, but the crafty man hides away his dishonour. Of this same thing to the Ephesians: Be angry, and sin not. Let not the sun set upon your wrath. Also in the Gospel according to Matthew: You have heard that it was said by the ancients, You shall not kill; and whoever shall kill shall be guilty of the judgment. But I say unto you, That every one who is angry with his brother without cause shall be guilty of the judgment.” (Treatise 12, Book 3:8).
“Let us then see if in this matter, as in others, we can perceive the Saviour mingling the newthings that flow from His own breasts with the wine of the ancients, on the occasion when Mary and Joseph searching found Him in the Temple, sitting in the midst of the doctors, both hearing them and asking them questions, and all …were astonished at His answers. But perhaps the glory o this figure is fulfilled in the place where, going up into a mountain, He taught the people and said: ‘It was said to them of old, “Thou shalt not kill…” But I say to you, whosoever is angry with his brother without reason shall be held guilty’; and, ‘It was said to them of old, “Thou shalt not commit adultery.” But I say to you, whosoever shall look on a woman to lust after her has already committed adultery with her in his heart.” (Homilies on the Song of Songs, Book 1, translated in R P Lawson, Ancient Christian Writers: The Song of Songs, Commentary and Homilies, Issue 26 (New York: Newman Press: 1988)).
Absent the phrase “without a cause” the Lord would be prohibiting all anger towards a brother, which is not biblical. Mark 3:5 describes our Lord being angry, saying, “And when he had looked round about on them with anger, being grieved for the hardness of their hearts, he saith unto the man, Stretch forth thine hand. And he stretched it out: and his hand was restored whole as the other.” As righteous anger is not sin, only anger “without a cause” is sin.