Daf 125b (דַּף קכ״ה ע״ב)

In this very manner, many bands of purity go forth into the world from that primordial Supernal Serpent in whom Adam was seduced (כְּגַוְונָא דָא כַּמָּה חֲבִילֵי טְהִירִין נָפְקֵי לְעַלְמָא מֵהַאי חִוְיָא עִלָּאָה קַדְמָאָה דְּאִתְפַּתָּא בֵּיהּ אָדָם), and all of them are appointed in concealment over the workings of the world (וְכֻלְהוּ מְמַנָּן בִּסְתִירוּ עוֹבָדֵי עַלְמָא), and therefore, when a son of man comes to purify himself, they aid him from above (וּבְגִין כָּךְ אָתֵי בַּר נָשׁ לְאִתְדַּכָּאָה, מְסַיְיעִין לֵיהּ מִלְּעֵילָא), and the assistance of his Master bargains for him and he is guarded and called holy (וְסִיּוּעָא דְּמָארֵיהּ סַחֲרָא לֵיהּ וְאִסְתַּמַּר וְאִקְרֵי קָדוֹשׁ). When a son of man comes to defile himself, many bands of purity are made available to him (אָתֵי בַּר נָשׁ לְאִסְתָּאֲבָא, כַּמָּה חֲבִילִין טְהִירִין אִזְדַּמְּנוּ לֵיהּ). And all of them-traders-dwell in him and trade with him and defile him, and he is called impure (וְכֻלְהוּ סַחֲרָן שַׁרְיָין בֵּיהּ וּמְסַחֲרִין לֵיהּ וּמְסָאֲבִין לֵיהּ וְאִקְרֵי טָמֵא), and all of them go and proclaim before him: "Impure! Impure!" as you say (וְכֻלְּהוּ אָזְלֵי וּמַכְרְזֵי קַמֵּי, טָמֵא טָמֵא כְּמָה דְאַתְּ אָמֵר), “And he shall cry: Impure! Impure!” (Leviticus 13) (וְטָמֵא טָמֵא יִקְרָא). And all of them are tied to that primordial Serpent and concealed in many workings of the world (וְכֻלְּהוּ קְטִירִין בְּהַהוּא חִיוְיָא קַדְמוֹנִי וּסְתִירִין בְּכַמָּה עוֹבָדֵי עָלְמָא).

Rabbi Yitzchak and Rabbi Yosei were walking from Tiberias to Lod (רַבִּי יִצְחָק וְרִבִּי יוֹסֵי הֲווּ אָזְלֵי מִטְּבֶרְיָא לְלוֹד). Rabbi Yitzchak said: I am pained over that wicked one Bil‘am, for all the deeds of that wicked one were from the impure side (אָמַר רַבִּי יִצְחָק תְּוַוהֲנָא עַל הַהוּא רָשָׁע דְּבִלְעָם דְּכָל עוֹבָדוֹי דְהַהוּא רָשָׁע הֲווּ מִסִּטְרָא דִּמְסָאֲבָא). And here we have learned one secret, that all kinds of serpents in the world are all bound and go forth from that primordial Serpent, who is a defiled and polluted spirit (וְהָכָא אוֹלִיפְנָא רָזָא חָדָא, דְּכָל זִינֵי נְחָשַׁיָּא דְּעַלְמָא כֻּלְּהוֹן מִתְקַטְּרָן וְנָפְקִין מֵהַהוּא נָחָשׁ קַדְמוֹנִי דְּאִיהוּ רוּחַ מְסָאֲבָא מְזוּהֲמָא), and therefore all sorcerers of the world are called by the name of serpents (and scorpions), and all of them go out from this side (וּבְגִין כָּךְ כָּל חָרָשִׁין דְּעַלְמָא אִקְרוּן עַל שְׁמָא דָא נְחָשִׁים (ועקרבים) וְכֻלְּהוּ מֵהַאי סִטְרָא נָפְקֵי). And whoever is drawn to this-behold, he is defiled (וּמַאן דְּאִתְמְשַׁךְ בְּהַאי, הָא אִסְתָּאַב). And not only that, but he desires to defile himself in order to draw upon himself that side of the impure spirit (וְלָא עוֹד אֶלָּא דְּבָעֵי לְאִסְתָּאֲבָא בְּגִין לְאַמְשָׁכָא עֲלֵיהּ הַהוּא סִטְרָא דְּרוּחַ מְסָאֲבָא). For we have learned: Just as a son of man arouses himself, so is drawn upon him from above (דְּהָא תָּנִינָן כְּגַוְונָא דְאִתְעַר בַּר נָשׁ הָכִי נָמֵי אַמְשִׁיךְ עֲלֵיהּ מִלְּעֵילָא). If he arouses himself on the side of Kedushah, holiness is drawn upon him from above and he is sanctified (אִי אִיהוּ אִתְעַר בְּסִטְרָא דִקְדוּשָּׁה אַמְשִׁיךְ עֲלֵיהּ קְדוּשָּׁה מִלְּעֵילָא וְאִתְקַדַּשׁ). But if he arouses himself on the side of impurity, then an impure spirit is drawn upon him and he is defiled (וְאִי אִיהוּ אִתְעַר בְּסִטְרָא דִּמְסָאֲבָא הָכִי אַמְשִׁיךְ עֲלֵיהּ רוּחַ מְסָאֲבָא וְאִסְתָּאַב). For it is said on that which we have learned: If a son of man comes to defile himself-they defile him (דְּהָא אִתְּמָר עַל מַה דְּתָנִינָן אָתֵי בַּר נָשׁ לְאִסְתָּאֲבָא מְסָאֲבִין לֵיהּ).

Therefore that wicked one, Bil‘am, in order to draw upon himself the impure spirit from that Supernal Serpent, would defile himself each night with his she-ass (בְּגִין כָּךְ הַהוּא רָשָׁע דְּבִלְעָם, בְּגִין לְאַמְשָׁכָא עֲלֵיהּ רוּחַ מְסָאֲבָא מֵהַהוּא נָחָשׁ עִלָּאָה, הֲוָה אִסְתָּאַב בְּכָל לֵילְיָא בַּאֲתָנֵיהּ), and would perform with her acts of intercourse to defile himself and to draw upon himself the impure spirit (וְהֲוָה עָבִיד עִמַּהּ עוֹבָדֵי אִישׁוּת בְּגִין לְאִסְתָּאֲבָא וּלְאַמְשָׁכָא עֲלֵיהּ רוּחַ מְסָאֲבָא), and only then would he perform his sorceries and works (וּכְדֵין עֲבִיד חֳרָשׁוֹי וְעוֹבָדוֹי).