In 1 Samuel 11:6 (NASB)
Then the Spirit of God rushed upon Saul when he heard these words, and he became very angry.
Is anger a fruit of the Spirit?
The operative word translated "anger" in 1 Sam 11:6 is אַף = "nostril" or "nose".
To understand this, one must recall that Hebrew has no abstract nouns like "anger" and so must represent abstract entities with concrete nouns. This same word אַף also occurs in many places such as: Gen 2:7, 3:19 (sweat of your nose), 7:22, 19:1, 24:47, etc.
אַף is translated 'anger" in places like Gen 27:45, 49:6, 7, Ex 32:12, Deut 9:19, etc, presumably on the basis that an angry person begins to breath heavily via their nose. Such a human response is not confined to anger but is also associated with excitement, agitation and any other response to physiological human need immediately before a demanding task.
Even today, people often say when a person prepares for something very significant, "He took a deep breath and ..."
Thus, 1 Sam 11:6, if it be translated "anger" might be a holy anger, or better, a "righteous indignation" or channeled anger whereby something good is accomplished, in contradistinction to "blind anger and rage" that besets we humans at times.
Anger is not listed as the fruit (singular) of the Spirit that Christians cultivate, namely: Love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control (Galatians 5:22). However, the Spirit of God is unique.
The Spirit of God was involved in creation (Genesis 1:1-2).
When Samuel anointed David the Spirit of God came upon David in power (1 Samuel 16:13).
The Spirit of God empowered Samson to kill thirty, after which he returned to his father’s house “in hot anger” (1 Samuel 14:19).
The Spirit of God empowered the first Christians who were in Jerusalem at Pentecost (Acts 2:1-4).
The Spirit of God was the power responsible for the deaths of Ananias and Sapphira (Acts 5:1-11).
Because the Holy Spirit is God, then the attributes of God are manifest in His Spirit. He possesses a mind, emotions, and a will: “All these are empowered by one and the same Spirit, who apportions to each one individually as he wills” (1 Corinthians 12:11). He executes God’s judgments and does God’s will.
The Holy Spirit has been present with the Father and the Son since before time began. The Spirit is integral to all of the things that God is described as doing in the Bible.
Anger is not a “fruit of the Spirit” but it is a feature of His Person, an attribute that is dispensed according to the purpose of God.
Is anger a fruit of the Spirit? I don't think so.
To be sure, I'm offering a New Testament interpretation of an Old Testament text.
--
Fruit of the Spirit
22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
23 Meekness, temperance...(Galatians 5:22-23)
Contrast this with Paul's comments on the works of the flesh:
17 For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.
...
19 Now the works of the flesh are manifest, which are these; ...
20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, (Galations 5:17-20)
Anger seems a much better fit with the works of the flesh than the fruit of the Spirit.
--
Divine wrath
It could be that Saul was inspired with compassion for the men of Jabesh and simultaneously was angry at what the Ammonites were doing to them.
There are multiple instances in the Gospels where Jesus expresses anger, or, what some would refer to as Divine wrath. The cleansing of the temple is an example about which much has been written.
Based on Hebrews 4:15
For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin.
We can conclude that if Jesus was angry, His anger was justified. In other words, His wrath is an appropriate exhibition of Divine justice.
Although some may disagree, I am not convinced that there are examples in the Bible of anyone besides the Lord being angry in this way.
--
Saul in broader context
This suggests to me that Saul's anger is not a Divinely sanctioned response. What then do we make of it?
Let's assume for sake of argument that the Hebrew has been correctly translated--I did a quick survey of a variety of translations and found no significant disagreement as to emotion Saul exhibited.
While I suppose it's possible that Saul felt Divinely inspired anger at the wickedness of the Ammonites, I'm drawn to a different take on the text than others have shared: the Spirit inspired/impressed something upon Saul's mind and he didn't like it. He became angry because he didn't like God's instructions.
This burst of anger would fit with the pattern of behavior we see in Saul (anybody have a javelin handy?); he didn't like being told (by God or God's representative) to do something different from what he wanted to do (e.g. to obey is better than to sacrifice).
Saul's downfall was believing that he knew better than God what should be done. This episode then would be quite consistent--God inspired Saul to do one thing, and he didn't like it, so he became angry and sought to do something else.
--
Conclusion
A variety of interpretations are possible. I believe the interpretation that is most consistent with the character of Saul, and most consistent with the Biblical text in aggregate, is that God inspired Saul to do something contrary to Saul's will, and Saul became angry upon receiving this impression from God.
It would be fair to remember that Saul is not a one-dimensional character. He was at times a faithful servant of the Lord. At other times he struggled, repented, and tried again. But in the end it appears that his pride proved to be stronger than his commitment to the Lord. His downfall didn't come in a single moment, but was a gradual fall from grace. This passage exhibits that struggle.
Mark 3:5 He looked around at them in anger and, deeply distressed at their stubborn hearts, said to the man, "Stretch out your hand." He stretched it out, and his hand was completely restored.
Jesus was filled with the Spirit all the time and he was angry in Mark.