וְשָׁמַרְתָּ֞ אֶת־מִשְׁמֶ֣רֶת ׀ יְהוָ֣ה אֱלֹהֶ֗יךָ לָלֶ֤כֶת בִּדְרָכָיו֙ לִשְׁמֹ֨ר חֻקֹּתָ֤יו מִצְוֺתָיו֙ וּמִשְׁפָּטָ֣יו וְעֵדְוֺתָ֔יו כַּכָּת֖וּב בְּתוֹרַ֣ת מֹשֶׁ֑ה לְמַ֣עַן תַּשְׂכִּ֗יל אֵ֚ת כָּל־אֲשֶׁ֣ר תַּֽעֲשֶׂ֔ה וְאֵ֛ת כָּל־אֲשֶׁ֥ר תִּפְנֶ֖ה שָֽׁם׃
Beobachte die Vorschriften des Herrn deines Gottes, dass du auf seinen Wegen gehest, seine Satzungen wahrest, seine Gebote, seine Rechte und seine Zeugnisse, wie geschrieben ist in der Lehre Moses; damit du glücklich seiest in allem, was du thuest, und überall, wohin du dich wendest.
Mishneh Torah, Torah Study
Even as man is obliged to instruct his son, so is he obliged to teach his son's son, for it is said: "But make them known to thy sons and thy sons' sons" (Ibid. 4.9); and, not alone to his son and his son's son, but each and every scholar in Israel is commanded to instruct all who desire to be his disciples, even though they be not his sons, for it is said: "And thou shalt teach them diligently unto thy children" (Ibid. 6.7.), which is traditionally interpreted2Sifre, Deut. 11. C. G. to include one's disciples; for disciples, too, are called children, as it is said: "And the sons of the prophets came forth" (Second Kings, 2.3.). If it be so, why then was one commanded to teach his son and his son's son? To permit the precedence of one's son to one's son's son, and his son's son to the son of his fellow.3Sukkah, 30b; Kiddushin, 30. G.