In discussing the commandment of supporting the Levite, the Sefer HaChinukh explains the social and spiritual necessity of sustaining those devoted to divine service and instruction. It provides an ethical framework for supporting Torah personnel, though it is not a direct treatment of Yissachar–Zevulun.
לְהִדָּבֵק בְּחַכְמֵי הַתּוֹרָה – שֶׁנִּצְטַוִּינוּ לְהִתְחַבֵּר וּלְהִתְדַּבֵּק עִם חַכְמֵי הַתּוֹרָה, כְּדֵי שֶׁנִּלְמַד מֵהֶם מִצְווֹתֶיהָ הַנִּכְבָּדוֹת, וְיוֹרוּנוּ הַדֵּעוֹת הָאֲמִתִּיּוֹת בָּהּ שֶׁהֵם מְקַבְּלִים מֵהֶם, וְעַל זֶה נֶאֱמַר (דברים י, כ) וּבוֹ תִדְבָּק, וְנִכְפָּל הַצִּוּוּי בְּמָקוֹם אַחֵר, שֶׁנֶּאֱמַר וּלְדָבְקָה בוֹ (שם יא, כב), וְאָמְרוּ זִכְרוֹנָם לִבְרָכָה (כתובות קיא, ב), וְכִי אֶפְשָׁר לוֹ לְאָדָם לְהִדָּבֵק בַּשְּׁכִינָה, וְהָא כְּתִיב כִּי יְיָ אֱלֹהֶיךָ אֵשׁ אֹכְלָה הוּא (דברים ד, כד)? אֶלָּא הַדָּבֵק לְתַלְמִידֵי חֲכָמִים וּלְתַלְמִידֵיהֶם כְּאִלּוּ נִדְבָּק בּוֹ בָּרוּךְ הוּא, וּמִזֶּה לָמְדוּ רַבּוֹתֵינוּ זִכְרוֹנָם לִבְרָכָה לוֹמַר, שֶׁכָּל הַנּוֹשֵׂא בַּת תַּלְמִיד חָכָם וְהַמַּשִּׂיא בִּתּוֹ לְתַלְמִיד חָכָם וּמְהַנֵּהוּ מִנְּכָסָיו כְּאִלּוּ נִדְבָּק בִּשְׁכִינָה. וְעוֹד דָּרְשׁוּ בְּסִפְרֵי (פיסקא דללכת בדרכיו), וּלְדָבְקָה בּוֹ לְמֹד דִּבְרֵי אַגָּדָה שֶׁמִּתּוֹךְ כָּךְ אַתָּה מַכִּיר מִי שֶׁאָמַר וְהָיָה הָעוֹלָם.
To cling to Torah sages: That we were commanded to associate [with] and cling to Torah sages, so that we learn its glorious commandments from them, and they teach us the true opinions — which are received through them — about it. And about this is it stated (Deuteronomy 10:20), “to Him shall you cling.” And the command is repeated in another place, as it is stated (Deuteronomy 11:22), “and to cling to Him.” And they, may their memory be blessed, said (Ketuvot 111b), “And is it possible for a person to cling to the Divine Presence — and behold it is written (Deuteronomy 4:24), ‘For the Lord, your God, is a consuming fire’? Rather, one who clings to the Torah scholars and their students is as if he clings to Him, blessed be He.” And from this, our Rabbis, may their memory be blessed, learned that anyone who marries the daughter of a Torah scholar, or marries his daughter to a Torah scholar or who gives benefit from his property to a Torah scholar is as if he clings to the Divine presence. And they also expounded in Sifrei Devarim 49, “‘And to cling to Him’ — study the words of aggadah (the homiletical teachings), as through this, you will recognize the One Who spoke and the world came into being.”