To swear in His name, may He be blessed, truthfully: To swear in His name, blessed be He, at the time that we need to strengthen or establish a thing or to distance it; as with this is there aggrandizement of His statute, may He be blessed, and [of] the Power and the Loftiness. And about this is it stated (Deuteronomy 10:20) “and in His name shall you swear.” And in the explanation, they, may their memory be blessed, said (Shevuot 35b), “The Torah stated, ‘Swear in His name,’ and the Torah said, ‘Do not swear in His name’” — meaning to say, [just] like an oath that is not needed [should] be prevented, and that is a negative commandment; so too is an oath at a time that it is needed an obligation, and that is a positive commandment. And therefore we do not ever swear in [the name of] any thing of all the creatures. And they, may their memory be blessed, said (Sanhedrin 63a), “Anyone who combines the name of [God] with something else is uprooted from the world.” However this is said about one who intends to swear in that thing of the creatures by itself; but one who swears in the heavens or in the sun or in the moon, with the intention of the Master above them that created them — that is not included in the prohibition at all. And we always see that we swear like this in all of the borders of Israel.
It is from the roots of the commandment that in our establishing our words in His great name, the faith in Him and His supervision over us and over all our words are strengthened in our hearts. And that is a clear thing.
And I have written at great length about the laws of the commandment of oaths and vows in the Order of Vayishma Yitro (Sefer HaChinukh 30). (See Tur, Yoreh Deah 237.)
And it is practiced in every place and at all times by males and females. And one who transgresses this and does not want to swear in His name at a time it is needed has violated this positive commandment, according to Rambam, may his memory be blessed. But Ramban, may his memory be blessed, wrote (on Mitzvot Ase 7; Ramban on Deuteronomy 6:13) that an oath in His name [even] at a time of need is not a positive commandment at all; that if we want, we swear, and if we do not want to ever swear, there is no [problem] with this. And there is also a commandment in the prevention from an oath, like the matter that they said in Midrash Tanchuma, Matot 1, “The Holy One, blessed be He, said to them, ‘Do not reason that it is permitted to you to swear in My name even truthfully unless there is all of these characteristics with you: “The Lord, your God, you shall fear, and to Him shall you cling.” And afterwards, “and in His name shall you swear.”’” And if we want, we can say that “and in His name shall you swear” comes to give a positive commandment [alongside the] negative commandment on the one who swears in the name of idolatry; meaning to say, in His name should he swear and not in the name of other gods. And the teacher (Ramban), may his memory be blessed, already wrote about the matter that they, may their memory be blessed, said (Temurah 3b) that we swear to perform a commandment, that we derive it from “to Him shall you cling.”
לְהִשָּׁבַע בִּשְׁמוֹ יִתְבָּרַךְ בֶּאֱמֶת – לְהִשָּׁבַע בִּשְׁמוֹ בָּרוּךְ הוּא בְּעֵת שֶׁנִּצְטָרֵךְ לְהַחְזִיק וּלְקַיֵּם דָּבָר אוֹ לְהַרְחִיקוֹ, לְפִי שֶׁיֵּשׁ בָּזֶה גְּדֻלָּה בְּחֻקּוֹ יִתְבָּרַךְ, וְהַגְּבוּרָה וְהָרוֹמְמוּת, וְעַל זֶה נֶאֱמַר (דברים י כ) וּבִשְׁמוֹ תִּשָּׁבֵעַ, וּבְבֵאוּר אָמְרוּ זִכְרוֹנָם לִבְרָכָה (שבועות לה, ב) אָמְרָה תּוֹרָה הִשָּׁבַע בִּשְׁמוֹ, וְאָמְרָה תּוֹרָה אַל תִּשָּׁבַע, כְּלוֹמַר כִּי כְּמוֹ שֶׁהַשְּׁבוּעָה שֶׁאֵינָהּ צְרִיכָה הִיא נִמְנַעַת וְהִיא מִצְוַת לֹא תַעֲשֶׂה, כֵּן הַשְּׁבוּעָה בְּעֵת הַצֹּרֶךְ, הִיא חוֹבָה וְהִיא מִצְוַת עֲשֵׂה, וּלְפִיכָךְ, אֵין נִשְׁבָּעִין לְעוֹלָם בְּשׁוּם דָּבָר מִכָּל הַנִּבְרָאִים, וְאָמְרוּ זִכְרוֹנָם לִבְרָכָה (סנהדרין סג, א), כָּל הַמְשַׁתֵּף שֵׁם שָׁמַיִם וְדָבָר אַחֵר נֶעֱקָר מִן הָעוֹלָם. וְאָמְנָם זֶה נֶאֱמַר, בְּמֵי שֶׁמְּכַוֵּן לְהִשָּׁבַע בְּאוֹתוֹ דָּבָר מִן הַנִּבְרָאִין לְבַד, אֲבָל הַנִּשְׁבָּע בַּשָּׁמַיִם אוֹ בַּשֶּׁמֶשׁ וּבַיָּרֵחַ לְכַוָּנַת הָאָדוֹן שֶׁעֲלֵיהֶם שֶׁבְּרָאָם, זֶה אֵינוֹ בִּכְלַל הָאִסּוּר כְּלָל, וְתָמִיד נִרְאֶה שֶׁנִּשְׁבָּעִין כֵּן בְּכָל גְּבוּל יִשְׂרָאֵל.
To swear in His name, may He be blessed, truthfully: To swear in His name, blessed be He, at the time that we need to strengthen or establish a thing or to distance it; as with this is there aggrandizement of His statute, may He be blessed, and [of] the Power and the Loftiness. And about this is it stated (Deuteronomy 10:20) “and in His name shall you swear.” And in the explanation, they, may their memory be blessed, said (Shevuot 35b), “The Torah stated, ‘Swear in His name,’ and the Torah said, ‘Do not swear in His name’” — meaning to say, [just] like an oath that is not needed [should] be prevented, and that is a negative commandment; so too is an oath at a time that it is needed an obligation, and that is a positive commandment. And therefore we do not ever swear in [the name of] any thing of all the creatures. And they, may their memory be blessed, said (Sanhedrin 63a), “Anyone who combines the name of [God] with something else is uprooted from the world.” However this is said about one who intends to swear in that thing of the creatures by itself; but one who swears in the heavens or in the sun or in the moon, with the intention of the Master above them that created them — that is not included in the prohibition at all. And we always see that we swear like this in all of the borders of Israel.
מִשָּׁרְשֵׁי הַמִּצְוָה, כִּי בִּהְיוֹתֵנוּ מְקַיְּמִים דְּבָרֵינוּ בִּשְׁמוֹ הַגָּדוֹל תִּתְחַזֵּק בְּלִבֵּנוּ הָאֱמוּנָה בּוֹ וְהַשְׁגָּחָתוֹ עָלֵינוּ וְעַל כָּל דְּבָרֵינוּ, וְזֶה דָּבָר בָּרוּר.
It is from the roots of the commandment that in our establishing our words in His great name, the faith in Him and His supervision over us and over all our words are strengthened in our hearts. And that is a clear thing.
וּבְדִינֵי מִצְוַת הַשְּׁבוּעוֹת וְהַנְּדָרִים. הֶאֱרַכְתִּי בָּהֶם הַרְבֵּה בְּסֵדֶר "וַיִּשְׁמַע יִתְרוֹ" (מצוה ל) [יו"ד סימן רלז].
And I have written at great length about the laws of the commandment of oaths and vows in the Order of Vayishma Yitro (Sefer HaChinukh 30). (See Tur, Yoreh Deah 237.)
וְנוֹהֶגֶת בְּכָל מָקוֹם וּבְכָל זְמַן בִּזְכָרִים וּנְקֵבוֹת, וְהָעוֹבֵר עַל זֶה וְלֹא רָצָה לְהִשָּׁבַע בִּשְׁמוֹ לְעֵת הַצֹּרֶךְ בִּטֵּל עֲשֵׂה זֶה, לְדַעַת הָרַמְבַּ"ם זִכְרוֹנוֹ לִבְרָכָה, אֲבָל הָרַמְבַּ"ן זִכְרוֹנוֹ לִבְרָכָה כָּתַב (מ"ע ז ובפי' לדברים ו יג) שֶׁאֵין הַשְּׁבוּעָה בִּשְׁמוֹ גַּם בְּעֵת הַצֹּרֶךְ מִצְוַת עֲשֵׂה כְּלָל, כִּי אִם רְשׁוּת גְּמוּרָה, שֶׁאִם נִרְצֶה נִשָּׁבַע, וְאִם לֹא נִרְצֶה לְהִשָּׁבַע לְעוֹלָם אֵין בְּכָךְ כְּלוּם, וְגַם כִּי יֵשׁ בַּמְּנִיעָה מֵהַשְּׁבוּעָה מִצְוָה, וּכְעִנְיָן שֶׁאָמְרוּ בְּמִדְרַשׁ רַבִּי תַּנְחוּמָא (מטות א) אָמַר לָהֶם הַקָּדוֹשׁ בָּרוּךְ הוּא לְיִשְׂרָאֵל לֹא תִּהְיוּ סְבוּרִים שֶׁהֻתַּר לָכֶם לְהִשָּׁבַע בִּשְׁמִי אֲפִלּוּ בֶּאֱמֶת, אֶלָּא אִם כֵּן יִהְיוּ בְּךָ כָּל הַמִּדּוֹת הָאֵלֶּה אֶת יְיָ אֱלֹהֶיךָ תִּירָא, וְאוֹתוֹ תַעֲבֹד, וּבוֹ תִדְבָּק, וְאַחַר כָּךְ וּבִשְׁמוֹ תִּשָּׁבֵעַ. וְאִם נִרְצֶה נוּכַל לוֹמַר שֶׁיָּבוֹא וּבִשְׁמוֹ תִּשָּׁבֵעַ לִתֵּן עֲשֵׂה וְלֹא תַעֲשֶׂה לַנִּשְׁבָּע בְּשֵׁם עֲבוֹדָה זָרָה, כְּלוֹמַר, בִּשְׁמוֹ תִּשָּׁבֵעַ וְלֹא בְּשֵׁם אֱלֹהִים אֲחֵרִים. וְעִנְיַן מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (תמורה ג ב), שֶׁנִּשְׁבָּעִים לְקַיֵּם הַמִּצְוָה כְּבָר כָּתַב הָרַב זִכְרוֹנוֹ לִבְרָכָה, כִּי מִוּבוֹ תִדְבָּק נָפְקָא לָן.
And it is practiced in every place and at all times by males and females. And one who transgresses this and does not want to swear in His name at a time it is needed has violated this positive commandment, according to Rambam, may his memory be blessed. But Ramban, may his memory be blessed, wrote (on Mitzvot Ase 7; Ramban on Deuteronomy 6:13) that an oath in His name [even] at a time of need is not a positive commandment at all; that if we want, we swear, and if we do not want to ever swear, there is no [problem] with this. And there is also a commandment in the prevention from an oath, like the matter that they said in Midrash Tanchuma, Matot 1, “The Holy One, blessed be He, said to them, ‘Do not reason that it is permitted to you to swear in My name even truthfully unless there is all of these characteristics with you: “The Lord, your God, you shall fear, and to Him shall you cling.” And afterwards, “and in His name shall you swear.”’” And if we want, we can say that “and in His name shall you swear” comes to give a positive commandment [alongside the] negative commandment on the one who swears in the name of idolatry; meaning to say, in His name should he swear and not in the name of other gods. And the teacher (Ramban), may his memory be blessed, already wrote about the matter that they, may their memory be blessed, said (Temurah 3b) that we swear to perform a commandment, that we derive it from “to Him shall you cling.”