וַיְדַבֵּ֤ר מֹשֶׁה֙ אֶל־הָעָ֣ם לֵאמֹ֔ר הֵחָלְצ֧וּ מֵאִתְּכֶ֛ם אֲנָשִׁ֖ים לַצָּבָ֑א וְיִהְיוּ֙ עַל־מִדְיָ֔ן לָתֵ֥ת נִקְמַת־יְהוָ֖ה בְּמִדְיָֽן׃
And Moses spoke unto the people, saying: ‘Arm ye men from among you for the war, that they may go against Midian, to execute the LORD’S vengeance on Midian.
Read Kabbalistic (mystical) interpretations of Numbers 31:3: Zohar and classical Jewish mystical sources, free online.