Daf 138b (דַּף קַל״ח ע״ב)

And come and see (וְתָא חֲזֵי), Ya'akov knew that Esav was cleaving to that crooked Serpent (יַעֲקֹב הֲוָה יָדַע דְּעֵשָׂו הֲוָה לֵיהּ לְאִתְדַּבְּקָא בְּהַהוּא חִוְיָא עֲקִימָא), and for that reason in all his actions he drew upon himself as a different crooked Serpent (וְעַל דָּא בְּכָל עוֹבָדוֹי אִתְמַשִּׁיךְ עֲלֵיהּ כְּחִוְיָא עֲקִימָא אָחֳרָא), with Chokhmah in crookedness (בְּחָכְמְתָא בְּעֲקִימוּ), and so it was necessary (וְהָכִי אִצְטְרִיךְ). And this aligns with what Rabbi Shim'on said (וְאַתְיָיא דָא, כִּי הָא דְּאָמַר רִבִּי שִׁמְעוֹן): What is written, “And Elohim created the great sea monsters…” (Bereshit 1) (מַאי דִכְתִיב וַיִּבְרָא אֱלֹהִים אֶת הַתַּנִּינִים הַגְּדוֹלִים)? These are Ya'akov and Esav (דָּא יַעֲקֹב וְעֵשָׂו). “And every living creature that creeps” (Bereshit 1) (וְאֶת כָּל נֶפֶשׁ הַחַיָּה הָרוֹמֶשֶׂת)-these are the other degrees between them (אִלֵּין שְׁאָר דַּרְגִּין דְּבֵינַיְיהוּ). Indeed, Ya'akov was made wise to oppose that other Serpent (וַדַּאי אִתְעֲבִיד יַעֲקֹב חַכִּים לְקֳבְלֵיהּ דְּהַהוּא חִוְיָא אָחֳרָא), and so it was necessary (וְהָכִי אִצְטְרִיךְ). And for this reason (וּבְגִין כָּךְ), in every month there is one goat offered (בְּכָל יַרְחָא וְיַרְחָא חַד שָׂעִיר), in order to draw him to his place and separate him from the Moon (בְּגִין לְאַמְשָׁכָא לֵיהּ לְאַתְרֵיהּ וְיִתְפְּרַשׁ מִן סִיהֲרָא). And likewise on Yom Kippur, that goat is offered (וְכֵן בְּיוֹמֵי דְכִפּוּרִי לְאַקְרָבָא הַהוּא שָׂעִיר), and this is with Chokhmah, to dominate over him (וְדָא בְּחָכְמָה לְשַׁלְטָאָה עֲלֵיהּ), and he is not able to deceive (וְלָא יָכִיל לְאַבְאָשָׁא), as it is written, “and the goat shall bear upon him all their iniquities to a desolate land…” (Leviticus 16) (דִּכְתִיב וְנָשָׂא הַשָּׂעִיר עָלָיו אֶת כָּל עֲוֹנוֹתָם אֶל אֶרֶץ גְּזֵרָה). And it has been established that this is Esav, who is the goat (וְאוּקְמוּהָ דְּדָא עֵשָׂו דְּאִיהוּ שָׂעִיר), and all is in Chokhmah and in cunning toward him (וְכֹלָּא בְּחָכְמָה וּבְרַמָּאוּת לְגַבֵּיהּ). What is the reason? Because it is written, “and with the crooked You are wily” (מַאי טַעְמָא, מִשּׁוּם דִּכְתִיב וְעִם עִקֵּשׁ תִּתְפַּתָּל), for he is an evil Serpent (בְּגִין דְּאִיהוּ חִוְיָא בִּישָׁא), crooked of spirit (עָקִים רוּחָא), wise in deception (חַכִּים לְאַבְאָשָׁא), he twists above and he twists below (אַסְטֵי לְעֵילָא וְאַסְטֵי לְתַתָּא).