In Tanya, the Alter Rebbe explains the spiritual implications of following Beit Hillel, relating it to pathways of loving-kindness, which aligns with Divine mercy.
וְלָכֵן מָצִינוּ כַּמָּה דְבָרִים מִקּוּלֵּי בֵּית שַׁמַּאי וּמֵחוּמְרֵי בֵּית הִלֵּל, לְלַמְּדֵנוּ, שֶׁאַף בֵּית שַׁמַּאי שֶׁשֹּׁרֶשׁ נִשְׁמָתָם מִבְּחִינַת שְׂמֹאל הָעֶלְיוֹן, וְלָכֵן הָיוּ דָנִין לְהַחֲמִיר תָּמִיד בְּכָל אִיסּוּרֵי הַתּוֹרָה, וּבֵית הִלֵּל שֶׁהָיוּ מִבְּחִינַת יָמִין הָעֶלְיוֹן, הָיוּ מְלַמְּדִין זְכוּת לְהָקֵל וּלְהַתִּיר אִיסּוּרֵי בֵּית שַׁמַּאי, שֶׁיִּהְיוּ מוּתָּרִים מֵאִיסּוּרָם וְיוּכְלוּ לַעֲלוֹת לְמַעְלָה, אַף־עַל־פִּי־כֵן, בְּכַמָּה דְבָרִים הָיוּ בֵּית שַׁמַּאי מְקִילִּין, מִפְּנֵי הִתְכַּלְלוּת שֹׁרֶשׁ נִשְׁמָתָם שֶׁהוּא כָּלוּל גַּם מִיָּמִין. וְכֵן שׁוֹרֶשׁ נִשְׁמַת בֵּית הִלֵּל כָּלוּל גַּם מִשְּׂמֹאל, כַּיָּדוּעַ דֶּרֶךְ וּמִדּוֹת קֹדֶשׁ הָעֶלְיוֹן, דְּ״לֵית תַּמָן קִיצּוּץ וּפֵירוּד״ חַס וְשָׁלוֹם, וְכָל הַמִּדּוֹת כְּלוּלוֹת זוֹ מִזּוֹ, וְלָכֵן הֵם מְיוּחָדוֹת זוֹ בָּזוֹ, כַּיָּדוּעַ לְיוֹדְעֵי חֵן; וּכְדִכְתִיב בְּאַבְרָהָם, שֶׁהוּא מִדַּת הַחֶסֶד וְהָאַהֲבָה: ״עַתָּה יָדַעְתִּי כִּי יְרֵא אֱלֹהִים אַתָּה״, עַל־יְדֵי שֶׁלָּבַשׁ מִדַּת הַגְּבוּרָה, ״וַיַּעֲקוֹד אֶת יִצְחָק בְּנוֹ . . וַיִּקַּח אֶת הַמַּאֲכֶלֶת כוּ׳״.
Thus we find various matters that are of the leniencies of Bet Shammai and of the stringencies of Bet Hillel. This comes to teach us that Bet Shammai, the root of whose soul is of the category of the supernal left—[that is why they always decided stringently regarding all the prohibitions of the Torah; but Bet Hillel, who were of the supernal right, would find favorable arguments to be lenient and to permit the injunctions of Bet Shammai so that these should become muttarim from their issur and able to ascend upward. Nevertheless]—in several matters, even Bet Shammai are lenient. This is so because of the inclusiveness of their soul’s root, which compounds the right as well. And, likewise, the root of Bet Hillel’s soul compounds the left also. For, as known of the mode and attributes of the kodesh ha’elyon, there is no cleavage and division there, Heaven forfend, and all the traits compound each other. Thus, they are united one with the other, as known to the students of Kabbalah. Thus it is written of Abraham, who is the attribute of chesed and love: “Now I know that you are fearful of G–d”—for he had donned the attribute of gevurah “and bound Isaac his son…and took the knife….”