The Edges of Anger
וַיִּֽחַר־אַ֤ף יְהֹוָה֙ בְּיִשְׂרָאֵ֔ל וַיְנִעֵם֙ בַּמִּדְבָּ֔ר אַרְבָּעִ֖ים שָׁנָ֑ה עַד־תֹּם֙ כׇּל־הַדּ֔וֹר הָעֹשֶׂ֥ה הָרַ֖ע בְּעֵינֵ֥י יְהֹוָֽה׃
יהוה, incensed at Israel, made them wander in the wilderness for forty years, until the whole generation that had provoked יהוה’s displeasure was gone.
וינעם. וַיְטַלְטְלֵם, מִן "נָע וָנָד" (בראשית ד):
וינעם means, AND HE MOVED THEM ABOUT; the word is of the same root as נע in (Genesis 4:12) “a wanderer (נע) and a vagabond”.
אף על פי שהכעס מידה רעה מאוד, מכל מקום צריך אדם להנהיג עצמו בקצת העתים במידת הכעס. כגון: לייסר הרשעים, ולהטיל אימה על בני ביתו, ולזרוק מוראו בתלמידים. וכשכועס על הרשעים, ישקול כעסו. לפי שאמר משה רבינו עליו השלום על ראובן וגד "תרבות אנשים חטאים" (במדבר לב יד) לכך בן בנו נעשה כהן לפסילים, ואף על פי שלשם שמים כעס. הכל צריך מידה, בכל דרכיו של אדם. ויִראה איך יעשה המצוות, בין בכעסו בין בשחקו.
Even though anger is a very bad quality, nevertheless, a man should conduct himself at times with the quality of anger. For example, when he rebukes the wicked, and when he desires to cause a spirit of awe and respect to dwell on the members of his household, and when he wants to obtain respect and even fear from his pupils. Even he who is angry with the wicked, must weigh the extent of his anger, for Moses, our teacher, upon whom is peace, said when he spoke wrathfully against Reuben and Gad : "A breed of sinful men" (Num. 32:14). And, therefore, we find that his descendant (the Levite mentioned in Judges 18:30) became a priest to idols, and this even though Moses was angry because he strove for the glory of God. Everything requires a proper measure in all a man's ways. A man should speak carefully how to do the commandments, whether he rebukes out of anger or rebukes joyously.
וְאִם־יָצֹ֥א יֵצֵ֖א הָרֹצֵ֑חַ אֶת־גְּבוּל֙ עִ֣יר מִקְלָט֔וֹ אֲשֶׁ֥ר יָנ֖וּס שָֽׁמָּה׃ וּמָצָ֤א אֹתוֹ֙ גֹּאֵ֣ל הַדָּ֔ם מִח֕וּץ לִגְב֖וּל עִ֣יר מִקְלָט֑וֹ וְרָצַ֞ח גֹּאֵ֤ל הַדָּם֙ אֶת־הָ֣רֹצֵ֔חַ אֵ֥ין ל֖וֹ דָּֽם׃
But if the killer ever goes outside the limits of the city of refuge to which he has fled, and the blood-avenger comes upon him outside the limits of his city of refuge, and the blood-avenger kills the killer, there is no bloodguilt on his account.
וְאִם־יָצֹ֥א יֵצֵ֖א הָרֹצֵ֑חַ אֶת־גְּבוּל֙ עִ֣יר מִקְלָט֔וֹ אֲשֶׁ֥ר יָנ֖וּס שָֽׁמָּה׃ וּמָצָ֤א אֹתוֹ֙ גֹּאֵ֣ל הַדָּ֔ם מִח֕וּץ לִגְב֖וּל עִ֣יר מִקְלָט֑וֹ וְרָצַ֞ח גֹּאֵ֤ל הַדָּם֙ אֶת־הָ֣רֹצֵ֔חַ אֵ֥ין ל֖וֹ דָּֽם׃
But if the killer ever goes outside the limits of the city of refuge to which he has fled, and the blood-avenger comes upon him outside the limits of his city of refuge, and the blood-avenger kills the killer, there is no bloodguilt on his account.

פסחים סו:ב

ריש לקיש אמר

כל אדם שכועס אם חכם הוא חכמתו מסתלקת ממנו אם נביא הוא נבואתו מסתלקת ממנו

אם חכם הוא חכמתו מסתלקת ממנו ממשה דכתיב ויקצוף משה על פקודי החיל וגו׳ וכתיב ויאמר אלעזר הכהן אל אנשי הצבא הבאים למלחמה זאת חקת התורה אשר צוה ה׳ את משה וגו׳ מכלל דמשה איעלם מיניה

Psachim 66:b

Similarly, Reish Lakish said: Any person who becomes angry, if he is aTorah scholar, his wisdom departs from him, and if he is a prophet, his prophecy departs from him. The Gemara explains: That if he is a Torah scholar his wisdom departs from him is learned from Moses, as it is written: “And Moses became angry with the officers of the host, the captains over thousands and the captains over hundreds, who came from the battle” (Numbers 31:14). And what was his punishment? As it is written afterward: “And Elazar the priest said to the men of war who went to the battle: This is the statute of the law, which the Lord commanded Moses” (Numbers 31:21), which proves by inference that this law had become hidden from Moses due to his anger.

(ג) וְיֵשׁ דֵּעוֹת שֶׁאָסוּר לוֹ לָאָדָם לִנְהֹג בָּהֶן בְּבֵינוֹנִית אֶלָּא יִתְרַחֵק מִן הַקָּצֶה הָאֶחָד עַד הַקָּצֶה הָאַחֵר....

וְכֵן הַכַּעַס מִדָּה רָעָה הִיא עַד לִמְאֹד וְרָאוּי לָאָדָם שֶׁיִּתְרַחֵק מִמֶּנָּה עַד הַקָּצֶה הָאַחֵר. וִילַמֵּד עַצְמוֹ שֶׁלֹּא יִכְעֹס וַאֲפִלּוּ עַל דָּבָר שֶׁרָאוּי לִכְעֹס עָלָיו. וְאִם רָצָה לְהַטִּיל אֵימָה עַל בָּנָיו וּבְנֵי בֵּיתוֹ אוֹ עַל הַצִּבּוּר אִם הָיָה פַּרְנָס וְרָצָה לִכְעֹס עֲלֵיהֶן כְּדֵי שֶׁיַּחְזְרוּ לַמּוּטָב יַרְאֶה עַצְמוֹ בִּפְנֵיהֶם שֶׁהוּא כּוֹעֵס כְּדֵי לְיַסְּרָם וְתִהְיֶה דַּעְתּוֹ מְיֻשֶּׁבֶת בֵּינוֹ לְבֵין עַצְמוֹ כְּאָדָם שֶׁהוּא מְדַמֶּה כּוֹעֵס בִּשְׁעַת כַּעֲסוֹ וְהוּא אֵינוֹ כּוֹעֵס. אָמְרוּ חֲכָמִים הָרִאשׁוֹנִים כָּל הַכּוֹעֵס כְּאִלּוּ עוֹבֵד עֲבוֹדַת כּוֹכָבִים. וְאָמְרוּ שֶׁכָּל הַכּוֹעֵס אִם חָכָם הוּא חָכְמָתוֹ מִסְתַּלֶּקֶת מִמֶּנּוּ וְאִם נָבִיא הוּא נְבוּאָתוֹ מִסְתַּלֶּקֶת מִמֶּנּוּ. וּבַעֲלֵי כַּעַס אֵין חַיֵּיהֶם חַיִּים. לְפִיכָךְ צִוּוּ לְהִתְרַחֵק מִן הַכַּעַס עַד שֶׁיַּנְהִיג עַצְמוֹ שֶׁלֹּא יַרְגִּישׁ אֲפִלּוּ לַדְּבָרִים הַמַּכְעִיסִים וְזוֹ הִיא הַדֶּרֶךְ הַטּוֹבָה. וְדֶרֶךְ הַצַּדִּיקִים הֵן עֲלוּבִין וְאֵינָן עוֹלְבִין שׁוֹמְעִים חֶרְפָּתָם וְאֵינָם מְשִׁיבִין עוֹשִׂין מֵאַהֲבָה וּשְׂמֵחִים בְּיִסּוּרִים. וַעֲלֵיהֶם הַכָּתוּב אוֹמֵר (שופטים ה לא) "וְאֹהֲבָיו כְּצֵאת הַשֶּׁמֶשׁ בִּגְבֻרָתוֹ":

(3) And, yet, there are certain tendencies which man is forbidden to follow in the middle-way, but must distance himself from extreme to extreme....

So is anger an extremely evil tendency and it is proper for man to remove himself from it to the other extreme. One should teach himself not to get angry, even over a matter which befits anger. If one desires to engender awe in his children and his household, or in the public, if he be at the head of a community, even if he desire to get angry at them so as to bring them back to the good way, he should only act angry in their presence so as to reprove them, but his disposition must remain calm within himself, even as a man imitates, who is angry when the time calls forth anger but in reality he is not angry. The sages of yore said: "He who yields to anger is as if he worshiped idolatry".1See Nedarim, 22b. G. They also said: "Whosoever yields to anger, if he be a wise man his wisdom leaves him, and if he be a prophet his prophecy leaves him."2Pesahim, 66b. C. Verily the life of irritable persons is no life.3Pesahim, 113a. C. They have, therefore, commanded to be afar from anger, so that one will train himself not to mind even the things which do cause irritation, for such is the good way. The conduct of the just is to take insults but not give insults, hear themselves flouted but make no reply, do their duty as a work of love, and bear affliction cheerfully. Concerning them the Verse says: "But may those that love Him be as the rising of the sun in his might" (Judg. 5.31).