2כְּשֵׁם שֶׁחַיָּב אָדָם לְלַמֵּד אֶת בְּנוֹ כָּךְ הוּא חַיָּב לְלַמֵּד אֶת בֶּן בְּנוֹ שֶׁנֶּאֱמַר (דברים ד ט) "וְהוֹדַעְתָּם לְבָנֶיךָ וְלִבְנֵי בָנֶיךָ". וְלֹא בְּנוֹ וּבֶן בְּנוֹ בִּלְבַד אֶלָּא מִצְוָה עַל כָּל חָכָם וְחָכָם מִיִּשְׂרָאֵל לְלַמֵּד אֶת כָּל הַתַּלְמִידִים אַף עַל פִּי שֶׁאֵינָן בָּנָיו. שֶׁנֶּאֱמַר (דברים ו ז) "וְשִׁנַּנְתָּם לְבָנֶיךָ" מִפִּי הַשְּׁמוּעָה לָמְדוּ בָּנֶיךָ אֵלּוּ תַּלְמִידֶיךָ שֶׁהַתַּלְמִידִים קְרוּיִין בָּנִים שֶׁנֶּאֱמַר (מלכים ב ב ג) "וַיֵּצְאוּ בְנֵי הַנְּבִיאִים". אִם כֵּן לָמָּה נִצְטַוָּה עַל בְּנוֹ וְעַל בֶּן בְּנוֹ. לְהַקְדִּים בְּנוֹ לְבֶן בְּנוֹ וּבֶן בְּנוֹ לְבֶן חֲבֵרוֹ:
Just as a person is obligated to teach his son, so too he is obligated to teach his grandson, as it says, "And make them known to your children, and to your children's children" (Deut 4:9). And not just his son and his grandson: rather, there is a command upon each and every wise-man [heb. chacham] in Israel to teach all students, even though they are not his children. As it says, "And you shall tutor them to your children" (Deut 6:7) - from an [Oral] Tradition they learned that "your children" [here] refers to your students, for students can be called children, as in "And the children of the prophets left" (I Kings 2:3). If so, why was it [i.e. the obligation to teach] commanded in regard to a son and grandson? To give priority to a son over a grandson, and a grandson over the son of a friend.