Numbers 31:3

וידבר משה וגו׳ AND MOSES SPAKE etc. — Although he had heard (v. 2) that his death was associated with this matter, he did it gladly and did not delay (Sifrei Bamidbar 157:2). החלצו — Understand this as the Targum does in the sense of “equipped (חלוצי) for war”, armed. אנשים MEN — righteous men, and similar is, (Exodus 17:9) “Choose men for us”, and so, too, (Deuteronomy 1:13) “men wise and well-known” (Midrash Tanchuma, Matot 3). ‎'נקמת ה‎ “THE VENGEANCE OF THE LORD” — [This is really equivalent to the expression God had employed (v.2), “the vengeance of the children of Israel”], because whoever attacks Israel is as though he attacks the Holy One blessed be He.

And Moshe spoke to the people, saying, Arm from yourselves men for the army, and let them go against Midyan and avenge the Lord on Midyan.

וַיְדַבֵּ֤ר מֹשֶׁה֙ אֶל־הָעָ֣ם לֵאמֹ֔ר הֵחָלְצ֧וּ מֵאִתְּכֶ֛ם אֲנָשִׁ֖ים לַצָּבָ֑א וְיִהְיוּ֙ עַל־מִדְיָ֔ן לָתֵ֥ת נִקְמַת־יְהֹוָ֖ה בְּמִדְיָֽן׃