In the King James Version, we find a statement that is lacking in the NIV and most modern versions of the Bible. “…Without a cause…” is left out.
“But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment…” (KJV)

What would be the reason for this?
To come to an objective answer, we use three criteria.

1. External criteria.

Our first criterion is to look at the manuscripts available that represent these variations.

Matthew 5:22

What immediately draws our attention is that the oldest Greek manuscript, the Papyrus 67 (±200 A.D.) together with three representatives of the Church Fathers before the year 200 A.D. all quote this verse without the indication “…without cause…). On the other hand the Diatessaron from the same period does have this indication. But the Diatessaron that Tatian the Syrian compiled in 170 A.D. is seen by Bible Experts as a document of low esteem. Tatian compiled the four gospels into one continuous narrative, adding some of his personal notes and leaving out portions as he pleased. Yet due to the convenience of having one instead of four gospels, his document was widely used and copied. Only much later the leaders in the Church realised that his document caused many alterations in the Greek texts. Then in was abolished and replaced with the original gospels.
It is noteworthy that Irenaeus (†202 A.D.) quoted this verse in his Latin writings without these words, but in his Greek writings with the phraze. Could it be that his Greek copy had already been influenced by the Diatessaron? Origen (†254 A.D.), Eusebius (†339 A.D.) and Augustine (†430 A.D.) also use both versions.
The Sinaiticus and the Vaticanus (±350 A.D.), both reckoned by Text experts as of the most reliable Greek manuscripts are without this phrase. The first Greek manuscripts with the phrase are the codices Bezae and Washingtoniensis of a hundred years later, both of much lower esteem. The later Greek manuscripts, all dating after 700 A.D. as well as most Antique Translation contain this phrase.

The manuscript evidence strongly calls for the variation without the phrase to represent the original autograph.

2. Internal criteria

Our next criterion is looking at a possible explanation of how a the variation could have originated.
Scribes could easily add a phrase as logic as this without even noticing it themselves, but for removing such a phrase from the text would require clear evidence. In this pericope no such reason is evident.
The original must have been without this phrase.

3. Intrinsic Evidence.
The third objective criterion is to look at the context and the function of the words under observation in the sentence itself. Would Jesus in fact have added this phrase, or would He rather have said or without this phrase?

Let us look at the context:
1) Matthew 5:17: “Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.”
Jesus wanted to explain how the Law should be “fulfilled”, or have its real meaning.
2) Verse 20: “For I say unto you, That except your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven.”
Would “without cause” not have been exactly what the scribes and Pharisees have said? But Jesus said that our righteousness should exceed what they teach.
3) Verse 22 b: “…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.”
Jesus emphasizes that it is about much more than just the letter of the Law.
4) Verse 23: “So if you are offering your gift at the altar and there remember that your brother has something against you…”
Once again Jesus places the responsibility not on the guilty brother, but on his follower.

From the context it is obvious that Jesus is stressing much more than just justified anger. He stresses that his follower has a responsibility that should come from within.

Looking at the function of this phrase within the sentence itself, it is clear from the others examples that Jesus mentioned that He is not talking about cases where there are any grounds for being angry at all. Being angry with your neighbour has already damaged the relationship, and that is already against the core of this law.

According to the context it is obvious that Jesus is talking about being angry per se, and not whether there are grounds for being angry or not.

4. Conclusion.
With all three objective criteria in favour of the version where the phrase “..without cause…” is lacking, that version should be chosen as representative of the original autograph.

God bless,

Herman.