The commandment of the unification of God: That we were commanded to believe that God, may He be blessed — Who is the Mover of all existence, the Master of everything — is one without any combination, as it is stated (Deuteronomy 6:4), “Hear, Israel, the Lord is our God, the Lord is one.” And this is a positive commandment, not [just] a statement. But the understanding of “Hear” is, “Accept from me this thing, and know it and believe in it — that the Lord, Who is our God, is one. And the proof that this is a positive commandment is their, may their memory be blessed, constantly saying in Midrash, “On the condition of unifying His name”; “in order to accept the yoke of the kingdom of Heaven upon himself” — meaning to say, the acknowledgement of unity and faith.
The root of this commandment is well-known, as it is the foundation of the faith of all people in the world and it is the strong pillar that every intelligent person relies upon.
From the laws of the commandment is that which they, may their memory be blessed, said (Berakhot 61b) that every Israelite is obligated about the commandment of unification; since anyone who does not acknowledge His unity, blessed be He, is as if he denies a fundamental principle [of faith] — as there is no complete [Divine] rulership and majesty without total unity, and the heart of every wise man will distinguish this. And if so, behold, this commandment is included in the prohibition of idolatry, about which we are commanded to be killed in every place and at any time. [This] and the rest of its details are scattered in the Midrash and in [various] places in the Gemara. And there, [there are also] many stories of several Israelites — big and small — may all their memory be blessed, who were killed for the sanctification of His unity, blessed be He.
And this commandment is practiced in every place and at all times by males and females. And one who transgresses it and does not believe in His unity, blessed be He, has violated this positive commandment [as well as] all of the other commandments of the Torah, since they are all dependent upon the belief in His divinity and unity. And he is called a denier of a fundamental principle [of faith], and he is not in the category of the Children of Israel, but rather in the category of sectarians. And God has separated him out for evil, but the one who believes in God and trusts in Him will be raised up. And this is one of the commandments that we said at the beginning of the book that a person is constantly obligated about, meaning to say that the obligation upon him never ceases, not even [for] a small instant.
מִצְוַת אַחְדוּת הַשֵּׁם – שֶׁנִּצְטַוִּינוּ לְהַאֲמִין כִּי הַשֵּׁם יִתְבָּרַךְ הוּא הַפּוֹעֵל כָּל הַמְּצִיאוּת, אֲדוֹן הַכֹּל, אֶחָד בְּלִי שׁוּם שִׁתּוּף, שֶׁנֶּאֱמַר (דברים ו ד) שְׁמַע יִשְׂרָאֵל יְיָ אֱלֹהֵינוּ יְיָ אֶחָד, וְזֶה מִצְוַת עֲשֵׂה הִיא, אֵינָהּ הַגָּדָה, אֲבָל פֵּרוּשׁ שְׁמַע כְּלוֹמַר, קַבֵּל מִמֶּנִּי דָּבָר זֶה וְדָעֵהוּ וְהַאֲמֵן בּוֹ, כִּי הַשֵּׁם שֶׁהוּא אֱלֹהֵינוּ אֶחָד הוּא. וְהָרְאָיָה שֶׁזּוֹ הִיא מִצְוַת עֲשֵׂה אָמְרָם זִכְרוֹנָם לִבְרָכָה תָּמִיד בַּמִּדְרָשִׁים עַל מְנָת לְיַחֵד שְׁמוֹ, כְּדֵי לְקַבֵּל עָלָיו מַלְכוּת שָׁמַיִם, כְּלוֹמַר הַהוֹדָאָה בַּיִּחוּד וְהָאֱמוּנָה.
The commandment of the unification of God: That we were commanded to believe that God, may He be blessed — Who is the Mover of all existence, the Master of everything — is one without any combination, as it is stated (Deuteronomy 6:4), “Hear, Israel, the Lord is our God, the Lord is one.” And this is a positive commandment, not [just] a statement. But the understanding of “Hear” is, “Accept from me this thing, and know it and believe in it — that the Lord, Who is our God, is one. And the proof that this is a positive commandment is their, may their memory be blessed, constantly saying in Midrash, “On the condition of unifying His name”; “in order to accept the yoke of the kingdom of Heaven upon himself” — meaning to say, the acknowledgement of unity and faith.
שֹׁרֶשׁ מִצְוָה זוֹ יָדוּעַ, כִּי זֶה עִקַּר אֱמוּנַת כָּל בְּנֵי הָעוֹלָם, וְהוּא הָעַמּוּד הֶחָזָק שֶׁלֵּב כָּל בֶּן דַּעַת סָמוּךְ עָלָיו.
The root of this commandment is well-known, as it is the foundation of the faith of all people in the world and it is the strong pillar that every intelligent person relies upon.
מִדִּינֵי הַמִּצְוָה. מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (ברכות סא, ב) שֶׁחַיָּב כָּל אֶחָד מִיִּשְׂרָאֵל לֵהָרֵג עַל מִצְוַת יִחוּד, לְפִי שֶׁכָּל שֶׁאֵינוֹ מוֹדֶה בְּיִחוּדוֹ בָּרוּךְ הוּא כְּאִלּוּ כּוֹפֵר בָּעִקָּר, שֶׁאֵין שְׁלֵמוּת הַמֶּמְשָׁלָה וְהַהוֹד אֶלָּא עִם הָאַחְדוּת הַגְּמוּרָה, וְלֵב כָּל חֲכַם לֵב יִבְחַן זֶה, וְאִם כֵּן הֲרֵי, מִצְוָה זוֹ מִכְּלַל אִסּוּר עֲבוֹדָה זָרָה, שֶׁאֲנַחְנוּ מְצֻוִּים לַהֲרֹג עָלֶיהָ בְּכָל מָקוֹם וּבְכָל שָׁעָה. וְיֶתֶר פְּרָטֶיהָ, מְפֻזָּרִין בַּמִּדְרָשׁוֹת וּבִמְקוֹמוֹת בַּגְּמָרָא, וְשָׁם מַעֲשִׂים הַרְבֵּה מִכַּמָּה בְּנֵי יִשְׂרָאֵל גְּדוֹלִים וּקְטַנִּים שֶׁנֶּהֶרְגוּ עַל קְדֻשַּׁת יִחוּדוֹ בָּרוּךְ הוּא, זֵכֶר כֻּלָּם לִבְרָכָה.
From the laws of the commandment is that which they, may their memory be blessed, said (Berakhot 61b) that every Israelite is obligated about the commandment of unification; since anyone who does not acknowledge His unity, blessed be He, is as if he denies a fundamental principle [of faith] — as there is no complete [Divine] rulership and majesty without total unity, and the heart of every wise man will distinguish this. And if so, behold, this commandment is included in the prohibition of idolatry, about which we are commanded to be killed in every place and at any time. [This] and the rest of its details are scattered in the Midrash and in [various] places in the Gemara. And there, [there are also] many stories of several Israelites — big and small — may all their memory be blessed, who were killed for the sanctification of His unity, blessed be He.
וְנוֹהֶגֶת מִצְוָה זוֹ בְּכָל מָקוֹם וּבְכָל זְמַן בִּזְכָרִים וּנְקֵבוֹת, וְהָעוֹבֵר עַל זֶה וְאֵינוֹ מַאֲמִין בְּיִחוּדוֹ בָּרוּךְ הוּא בִּטֵּל עֲשֵׂה זֶה וְגַם כָּל שְׁאָר מִצְוֹת הַתּוֹרָה. כִּי כֻּלָּן תְּלוּיוֹת בֶּאֱמוּנַת אֱלֹהוּתוֹ וְיִחוּדוֹ, וְנִקְרָא כּוֹפֵר בָּעִקָּר, וְאֵינוֹ מִכְּלַל בְּנֵי יִשְׂרָאֵל, אֶלָּא מִכְּלַל הַמִּינִין, וְהִבְדִּילוֹ הַשֵּׁם לְרָעָה, וְהַמַּאֲמִין בַּשֵּׁם וּבוֹטֵחַ בּוֹ יִשָּׂגֵב. וְזֹאת אַחַת מִן הַמִּצְוֹת שֶׁאָמַרְנוּ בִּתְחִלַּת הַסֵּפֶר שֶׁהָאָדָם חַיָּב בָּהֶן בְּהַתְמָדָה, כְּלוֹמַר שֶׁלֹּא יִפָּסֵק חִיּוּבָן מֵעָלָיו לְעוֹלָם, וַאֲפִלּוּ רֶגַע קָטָן.
And this commandment is practiced in every place and at all times by males and females. And one who transgresses it and does not believe in His unity, blessed be He, has violated this positive commandment [as well as] all of the other commandments of the Torah, since they are all dependent upon the belief in His divinity and unity. And he is called a denier of a fundamental principle [of faith], and he is not in the category of the Children of Israel, but rather in the category of sectarians. And God has separated him out for evil, but the one who believes in God and trusts in Him will be raised up. And this is one of the commandments that we said at the beginning of the book that a person is constantly obligated about, meaning to say that the obligation upon him never ceases, not even [for] a small instant.