The midrash on Matos links the laws of vows, the war against Midian, and the leadership of Moshe to deeper themes of speech, discipline, and sanctifying the ordinary. It offers homiletic openings for mussar on self-control and the seriousness of commitment.
וַיְדַבֵּר משֶׁה אֶל רָאשֵׁי הַמַּטּוֹת, אִישׁ כִּי יִדֹּר נֶדֶר לַה' (במדבר ל, ב ג), הֲדָא הוּא דִּכְתִיב (ירמיה ד, ב): וְנִשְׁבַּעְתָּ חַי ה' בֶּאֱמֶת בְּמִשְׁפָּט וּבִצְדָקָה, אָמַר לָהֶם הַקָּדוֹשׁ בָּרוּךְ הוּא לְיִשְׂרָאֵל, לֹא תִהְיוּ סְבוּרִים שֶׁהֻתַּר לָכֶם לְהִשָּׁבַע בִּשְׁמִי אֲפִלּוּ בֶּאֱמֶת, אֵין אַתָּה רַשַּׁאי לְהִשָּׁבַע בִּשְׁמִי אֶלָּא אִם כֵּן יִהְיוּ בְּךָ כָּל הַמִּדּוֹת הָאֵלּוּ (דברים י, כ): אֶת ה' אֱלֹהֶיךָ תִּירָא, שֶׁתְּהֵא כְּאוֹתָן שֶׁנִּקְרְאוּ יִרְאֵי אֱלֹהִים, אַבְרָהָם, אִיוֹב וְיוֹסֵף. אַבְרָהָם דִּכְתִיב (בראשית כב, יב): כִּי עַתָּה יָדַעְתִּי כִּי יְרֵא אֱלֹהִים אַתָּה, אִיּוֹב דִּכְתִיב (איוב א, ח): אִישׁ תָּם וְיָשָׁר יְרֵא אֱלֹהִים, יוֹסֵף דִּכְתִיב (בראשית מכ, יח): אֶת הָאֱלֹהִים אֲנִי יָרֵא, הֱוֵי אֶת ה' אֱלֹהֶיךָ תִּירָא. (דברים י, כ): וְאֹתוֹ תַעֲבֹד, אִם אַתָּה מְפַנֶּה עַצְמְךָ לַתּוֹרָה וְלַעֲסֹק בְּמִצְווֹת וְאֵין לְךָ עֲבוֹדָה אַחֶרֶת, לְכָךְ נֶאֱמַר: וְאֹתוֹ תַעֲבֹד. (דברים י, כ): וּבוֹ תִדְבָּק, וְכִי יָכוֹל אָדָם לִדָּבֵק בַּשְּׁכִינָה, וַהֲלֹא כְּבָר נֶאֱמַר (דברים ד, כד): כִּי ה' אֱלֹהֶיךָ אֵשׁ אֹכְלָה הוּא, אֶלָּא לוֹמַר לָךְ, כָּל הַמֵּשִׂיא בִּתּוֹ לְתַלְמִיד שֶׁקּוֹרֵא וְשׁוֹנֶה וְעוֹשֶׂה פְּרַקְמַטְיָא וּמְהַנֵּהוּ מִנְּכָסָיו, זֶהוּ שֶׁנֶּאֱמַר עָלָיו: וּבוֹ תִדְבָּק, אִם יֵשׁ בְּךָ כָּל הַמִּדּוֹת הָאֵלּוּ אַתָּה רַשַּׁאי לְהִשָּׁבַע, וְאִם לָאו אֵין אַתָּה רַשַּׁאי לְהִשָּׁבַע. מַעֲשֶׂה בְּיַנַּאי הַמֶּלֶךְ שֶׁהָיוּ לוֹ שְׁנֵי אֲלָפִים עֲיָרוֹת וְכֻלָּם נֶחֶרְבוּ עַל שְׁבוּעַת אֱמֶת, כֵּיצַד, אוֹמֵר אָדָם לַחֲבֵרוֹ בִּשְּׁבוּעָה שֶׁאֲנִי הוֹלֵךְ וְאוֹכֵל כָּךְ וְכָךְ בְּמָקוֹם פְּלוֹנִי, וְאֶשְׁתֶּה כָךְ וְכָךְ בְּמָקוֹם פְּלוֹנִי, וְהָיוּ הוֹלְכִין וּמְקַיְּמִין שְׁבוּעָתָן, וְנֶחֶרְבוּ. מַה הַנִּשְׁבָּע בֶּאֱמֶת כָּךְ, הַנִּשְׁבָּע עַל הַשֶּׁקֶר עַל אַחַת כַּמָּה וְכַמָּה. נְקֹם נִקְמַת בְּנֵי יִשְׂרָאֵל מֵאֵת הַמִּדְיָנִים אַחַר תֵּאָסֵף אֶל עַמֶּךָ (במדבר לא, ב), רַבִּי יְהוּדָה אוֹמֵר אִלּוּ הָיָה רוֹצֶה משֶׁה לִחְיוֹת כַּמָּה שָׁנִים הָיָה חַי, שֶׁאָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא נְקֹם וְאַחַר תֵּאָסֵף, תָּלָה הַכָּתוּב מִיתָתוֹ בְּמִדְיָן, אֶלָּא לְהוֹדִיעֲךָ שִׁבְחוֹ שֶׁל משֶׁה, אָמַר בִּשְׁבִיל שֶׁאֶחְיֶה יְעַכֵּב נִקְמַת יִשְׂרָאֵל, מִיָּד (במדבר לא, ג): וַיְדַבֵּר משֶׁה אֶל הָעָם לֵאמֹר הֵחָלְצוּ מֵאִתְּכֶם אֲנָשִׁים לַצָּבָא, אֲנָשִׁים, צַדִּיקִים. וּלְהַלָּן (שמות יז, ט): בְּחַר לָנוּ אֲנָשִׁים, וְכֵן (איוב ד, יג): בִּנְפֹל תַּרְדֵּמָה עַל אֲנָשִׁים. (במדבר לא, ג): לָתֵת נִקְמַת ה' בְּמִדְיָן, הַקָּדוֹשׁ בָּרוּךְ הוּא אָמַר: נִקְמַת בְּנֵי יִשְׂרָאֵל, וּמשֶׁה אָמַר: נִקְמַת ה' בְּמִדְיָן, אָמַר הַקָּדוֹשׁ בָּרוּךְ הוּא לָהֶם אֵינוֹ אֶלָּא דִּיקוֹ שֶׁלָּכֶם, שֶׁגָּרְמוּ לִי לְהַזִּיק אֶתְכֶם, אָמַר משֶׁה רִבּוֹן הָעוֹלָמִים, אִם הָיִינוּ עֲרֵלִים, אוֹ עוֹבְדֵי עֲבוֹדַת כּוֹכָבִים, אוֹ כּוֹפְרֵי מִצְווֹת, לֹא הָיוּ שׂוֹנְאִין אוֹתָנוּ וְאֵינָן רוֹדְפִין אַחֲרֵינוּ אֶלָּא בִּשְׁבִיל תּוֹרָה וּמִצְווֹת שֶׁנָּתַתָּ לָנוּ, הִלְכָּךְ הַנְּקָמָה שֶׁלְּךָ לָתֵת נִקְמַת ה' בְּמִדְיָן.
“Moses spoke to the heads of the tribes of the children of Israel, saying: This is the matter that the Lord commanded:” (Numbers 30:2). “If a man takes a vow to the Lord, or takes an oath to impose a prohibition upon himself, he shall not profane his word; he shall act in accordance with everything that emerges from his mouth” (Numbers 30:3). “Moses spoke to the heads of the tribes.… If a man takes a vow to the Lord” – that is what is written: “You will take an oath: As the Lord lives, in truth, in justice and in righteousness” (Jeremiah 4:2). The Holy One blessed be He said to Israel: Do not think that it is permitted for you to take an oath in My name, even truthfully. You are permitted to take an oath in My name only if all these attributes exist in you: “The Lord your God you shall fear […and by his name you shall take an oath]” (Deuteronomy 6:13, 10:20) – that you shall be like those who called God-fearing: Abraham, Job, and Joseph. Abraham, as it is written: “For now I know that you are God-fearing” (Genesis 22:12). Job, as it is written: “A virtuous and upright man, fearing God” (Job 1:8). Joseph, as it is written: “I fear God” (Genesis 42:18). That is, “the Lord your God you shall fear.” “Him you shall serve” (Deuteronomy 6:13, 10:20) – if you devote yourself to Torah and to engaging in mitzvot, and you have no other work; that is why it is stated: “Him you shall serve.” “To Him you shall cleave” (Deuteronomy 10:20) – can a person cleave to the Divine Presence? Is it not already stated: “For the Lord your God is a consuming fire” (Deuteronomy 4:24)? Rather, it is to say to you: Anyone who marries his daughter to a scholar who studies Bible and Mishna, and engages in commerce and benefits him [the scholar] from his property, this is the one in whose regard it is stated: “To Him you shall cleave.” If you have all these qualities you are permitted to take an oath, but if not, you are not permitted to take an oath, There was an incident involving King Yannai, who had two thousand cities and all of them were destroyed due to true oaths. How so? A person would say to another: ‘By oath that I am going and eating this and that in such and such place, and drinking this and that in such and such place.’ They would go and fulfill their oath, and they were destroyed. If for one who takes a true oath it is so, one who takes a false oath, all the more so. The Lord said to Moses, saying: (Numbers 31:1). “Take the vengeance of the children of Israel against the Midianites; then you will be gathered to your people” (Numbers 31:2). “Take the vengeance of the children of Israel against the Midianites; then you will be gathered to your people” – Rabbi Yehuda says: Had Moses sought to live several years, he could have lived, as the Holy One blessed be He said to him: “Take vengeance…then you will be gathered.” The verse made his death contingent upon Midian. This is, rather, to inform you of Moses’ praiseworthiness. He said: Will the vengeance of Israel be delayed so that I will live? Immediately, “Moses spoke to the people, saying: Select from among you men for the army” (Numbers 31:3). “Men” – righteous, and elsewhere: “Choose men for us” (Exodus 17:9), and likewise, “when slumber falls upon men” (Job 4:13). “To wreak the Lord’s vengeance against Midian” (Numbers 31:3) – the Holy One blessed be He said: “The vengeance of the children of Israel,” but Moses said: “The Lord’s vengeance.” The Holy One blessed be He said to them: ‘It is nothing other than your justice, as they caused Me to harm you.’ Moses said: ‘Master of the universe, were we uncircumcised, idolaters, or deniers of mitzvot, they would not hate us. They persecute us only due to the Torah and mitzvot that You gave to us. Therefore, it is Your vengeance’ – “to wreak the Lord’s vengeance against Midian.”