A man's sword against his fellow, a man's sword against his brother
Figuratively: brotherly strife, wars, and conflicts in which one turns against another.
("And they blew the three hundred trumpets, and the LORD set every man's sword against his fellow and against all the camp; and the camp fled as far as Beth-shittah" — Judges 7:22, and likewise: "And I will call for a sword against him throughout all my mountains, says the Lord GOD: every man's sword shall be against his brother" — Ezekiel 38:21)
Translation
Expression (Hebrew)
חֶרֶב אִישׁ בְּרֵעֵהוּ, חֶרֶב אִישׁ בְּאָחִיו
Definition (Hebrew)
בְּהַשְׁאָלָה: מְלֵחַת אַחִים, מִלְחָמוֹת וְעִמּוּתִים שֶׁל הָאֶחָד בַּשֵּׁנִי.
("וַיִּתְקְעוּ שְׁלֹשׁ מֵאוֹת הַשּׁוֹפָרוֹת וַיָּשֶׂם ה' אֵת חֶרֶב אִישׁ בְּרֵעֵהוּ וּבְכָל הַמַּחֲנֶה וַיָּנָס הַמַּחֲנֶה עַד בֵּית הַשִּׁטָּה"- שׁוֹפְטִים ז כב, וְכֵן:"וְקָרָאתִי עָלָיו לְכָל הָרַי חֶרֶב נְאֻם אֲדֹנָי ה' חֶרֶב אִישׁ בְּאָחִיו תִּהְיֶה"- יְחֶזְקֵאל לַח כא)