The Sefer HaChinukh presents the commandment to teach Torah as applying to one’s children and to all who seek instruction, emphasizing that Torah must be transmitted so that it is not forgotten from Israel.
מִצְוַת תַּלְמוּד תּוֹרָה – מִצְוַת עֲשֵׂה לִלְמֹד חָכְמַת הַתּוֹרָה וּלְלַמְּדָהּ, כְּלוֹמַר כֵּיצַד נַעֲשֶׂה הַמִּצְוֹת, וְנִשָּׁמֵר מִמָּה שֶׁמְּנָעָנוּ הָאֵל מִמֶּנּוּ, וְלָדַעַת גַּם כֵּן מִשְׁפְּטֵי הַתּוֹרָה עַל כִּוּוּן הָאֱמֶת, וְעַל כָּל זֶה נֶאֱמַר (דברים ו ז) וְשִׁנַּנְתָּם לְבָנֶיךָ, וְאָמְרוּ רַבּוֹתֵינוּ זִכְרוֹנָם לִבְרָכָה (ספרי שם) בָּנֶיךָ אֵלּוּ תַּלְמִידֶיךָ, וְכֵן אַתָּה מוֹצֵא שֶׁהַתַּלְמִידִים קְרוּיִים בָּנִים, שֶׁנֶּאֱמַר (מלכים ב ב ג) וַיֵּצְאוּ בְּנֵי הַנְּבִיאִים, וְשָׁם נֶאֱמַר וְשִׁנַּנְתָּם שֶׁיִּהְיוּ מְסֻדָּרִים בְּתוֹךְ פִּיךָ, כְּשֶׁאָדָם שׁוֹאַלְךָ דָּבָר אַל תְּהֵא מְגַמְגֵּם לוֹ, אֶלָּא תְּהֵא אוֹמֵר לוֹ מִיָּד. וְנִכְפְּלָה מִצְוָה זוֹ בִּמְקוֹמוֹת רַבִּים, שֶׁנֶּאֱמַר (דברים ה א) וּלְמַדְתֶּם וַעֲשִׂיתֶם וּלְמַעַן יִלְמְדוּ וְלִמַּדְתֶּם אֹתָם אֶת בְּנֵיכֶם (שם יא יט). מִדִּינֵי הַמִּצְוָה. מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (סוכה מב, א) מֵאֵימָתַי מַתְחִיל הָאָב לְלַמֵּד אֶת בְּנוֹ תּוֹרָה? מִשֶּׁיַּתְחִיל לְדַבֵּר מְלַמְּדוֹ, תּוֹרָה צִוָּה לָנוּ מֹשֶׁה (דברים לג ד), וּפָסוּק רִאשׁוֹן מִקְּרִיאַת שְׁמַע שֶׁהוּא שְׁמַע יִשְׂרָאֵל, וְאַחַר כָּךְ מְלַמְּדוֹ מְעַט מְעַט מִפְּסוּקֵי הַתּוֹרָה, עַד שֶׁיְּהֵא בֶּן שֵׁשׁ אוֹ בֶּן שֶׁבַע שֶׁמּוֹלִיכוֹ אֵצֶל מְלַמְּדֵי תִּינוֹקוֹת. וְרָאוּי לְכָל בֶּן דַּעַת שֶׁיִּתֵּן לִבּוֹ שֶׁלֹּא לְהַכְבִּיד עַל הַיֶּלֶד בַּלִּמּוּד בְּעוֹדֶנּוּ רַךְ הָאֵבָרִים וְרַךְ הַלֵּבָב, עַד שֶׁיִּגְדַּל וְיִתְחַזֵּק כֹּחַ לִבּוֹ וְתֹקֶף אֵיבָרָיו, וְעַצְמוֹתָיו יִמְלְאוּ מֹחַ, וְיוּכַל לִסְבֹּל יְגִיעַת הַלִּמּוּד, וְלֹא יִקְרֶנּוּ חֹלִי הַהִתְעַלְּפוּת בְּסִבַּת הַיְּגִיעָה הָרַבָּה עָלָיו, וְאוּלָם אַחַר הִתְחַזֵּק כֹּחוֹ וְיֵאוֹרוּ עֵינָיו לְהָבִין לְקוֹל מוֹרָיו, אָז רָאוּי וְכָשֵׁר הַדָּבָר, וּמְחֻיָּב לְהָבִיא צַוָּארוֹ בְּעֻלָּהּ שֶׁל תּוֹרָה, וְלֹא יְרַפּוּהוּ מִמֶּנָּה אֲפִלּוּ כְּחוּט הַשַּׂעֲרָה, וְיַשְׁקוּהוּ תָּמִיד מִיֵּין רִקְחָהּ וְיַאֲכִילוּהוּ מִדִּבְשָׁהּ. וְכֵן מֵעִנְיַן הַמִּצְוָה מָה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (קדושין ל, א) עַד הֵיכָן חַיָּב אָדָם לְלַמֵּד אֶת בְּנוֹ תּוֹרָה, אָמַר רַב יְהוּדָה אָמַר שְׁמוּאֵל כְּגוֹן זְבוּלוּן בֶּן דָּן, פֵּרוּשׁ אָדָם שֶׁהָיָה בְּדוֹרָם, שֶׁשְּׁמוֹ כֵּן שֶׁלִּמְּדוֹ אֲבִי אָבִיו מִקְרָא, וּמִשְׁנָה, תַּלְמוּד, הֲלָכוֹת, וְאַגָּדוֹת. וְהִקְשׁוּ עַל זֶה בַּגְּמָרָא מַה שֶׁהִקְשׁוּ, וְהָיָה הַתֵּרוּץ שֶׁהַחִיּוּב לְלַמְּדָם מִקְרָא, דְּהַיְנוּ, תּוֹרָה, כְּמוֹ שֶׁעָשָׂה אֲבִי אָבִיו שֶׁל זְבוּלוּן, וְאַף עַל פִּי שֶׁזְּבוּלוּן בֶּן דָּן לִמְּדוֹ אֲבִי אָבִיו יוֹתֵר, וּמִי שֶׁהוֹסִיף עַל חִיּוּב הַמִּצְוָה כַּאֲבִי אָבִיו שֶׁל זְבוּלוּן בֶּן דָּן תָּבוֹא עָלָיו בְּרָכָה, וּמִי שֶׁלֹּא לִמְּדוּ אוֹתוֹ אֲבוֹתָיו שֶׁהֵם חַיָּבִין בָּזֶה כְּגוֹן אָבִיו וַאֲבִי אָבִיו, חַיָּב לְלַמֵּד עַצְמוֹ כְּשֶׁיִּהְיֶה גָּדוֹל וְיַכִּיר בַּדָּבָר, שֶׁנֶּאֱמַר וּלְמַדְתֶּם וַעֲשִׂיתֶם אֹתָם, וְאִם הָיוּ הָאָב וְהַבֵּן צְרִיכִין לִלְמֹד, וְאֵין בְּיָדוֹ שֶׁל אָב שֶׁיּוּכְלוּ שְׁנֵיהֶם לִלְמֹד תָּמִיד הוּא קוֹדֵם לִבְנוֹ, וְאִם בְּנוֹ נָבוֹן מִמֶּנּוּ וְתַלְמוּדוֹ מִתְקַיֵּם בְּיָדוֹ יוֹתֵר מִמֶּנּוּ בְּנוֹ קוֹדְמוֹ. וְעַד אֵימָתַי חַיָּב כָּל אָדָם לִלְמֹד תּוֹרָה? (רמב"ם תלמוד תורה א י) עַד יוֹם מוֹתוֹ, שֶׁנֶּאֱמַר (דברים ד ט) וּפֶן יָסוּרוּ מִלְּבָבְךָ כֹּל יְמֵי חַיֶּיךָ. וְעוֹד הִפְלִיגוּ חֲכָמִים בַּדָּבָר עַל דֶּרֶךְ הַמּוּסָר וּלְלַמֵּד בְּנֵי אָדָם חֵפֶץ וְאָמְרוּ (שבת פג ב), שֶׁאֲפִלּוּ בִּשְׁעַת מִיתָה חַיָּב אָדָם לִלְמֹד תּוֹרָה, שֶׁנֶּאֱמַר (במדבר יט יד) זֹאת הַתּוֹרָה אָדָם כִּי יָמוּת בְּאֹהֶל. וְכָל אֶחָד מִיִּשְׂרָאֵל חַיָּב בְּתַלְמוּד תּוֹרָה (יומא לה, ב) בֵּין עָנִי, בֵּין עָשִׁיר, בֵּין בָּרִיא, בֵּין בַּעַל יִסּוּרִין. וּכְבָר אָמְרוּ זִכְרוֹנָם לִבְרָכָה (עירובין נד א), שֶׁבְּעֵסֶק הַתּוֹרָה יִתְרַפְּאוּ כָּל הָאֵבָרִים. וַאֲפִלּוּ עָנִי הַמְּחַזֵּר עַל הַפְּתָחִים, וַאֲפִלּוּ בַּעַל אִשָּׁה וּבָנִים הַכֹּל חַיָּבִים לִקְבֹּעַ עִתִּים לַתּוֹרָה בַּיּוֹם וּבַלַּיְלָה, שֶׁנֶּאֱמַר (יהושע א ח) וְהָגִיתָ בּוֹ יוֹמָם וָלַיְלָה.
The commandment of Torah study: The positive commandment to study the wisdom of the Torah and to teach it; meaning to say how we should perform the commandments, guard ourselves from that which God prevented us and to also know the laws of the Torah according to their true intention. And about all of this is it stated (Deuteronomy 6:7), “You shall teach them to your sons.” And our Rabbis, may their memory be blessed, said (Sifrei Devarim 34:4), “‘Your sons’ — these are your students. And thus do you find that students are called sons, as it is stated (II Kings 2:3), ‘And the sons of the prophets went out.’” And it is [also] said there (Sifrei Devarim 34:1), “‘And you shall teach them (shinantam, which sounds like the word for tooth, hence, make them sharp like a tooth)’ — they shall be ordered in your mouth, so that if a person questions you [concerning them], you will not stammer to him, but answer him forthwith.” And this commandment is repeated in many places, as it is stated (Deuteronomy 5:1), “and study them and do them,” “and in order that you will study them” (Deuteronomy 31:12), “and you shall teach them to your children” (Deuteronomy 11:19). From the laws of the commandment: That which they, may their memory be blessed, said (Sukkah 42a) [that] from when does a father begin to teach his son Torah? From when he begins to speak, he should teach him, “Moshe commanded us the Torah” (Deuteronomy 33:4), and the first verse from the recitation of Shema, which is “Hear Israel” (Deuteronomy 6:4). And afterwards he teaches him a little [at a time] of the verses of the Torah, until he is six or seven, when he takes him to a teacher of young children. And it is fitting for every intelligent person to put his heart to not overburden the child with study when he is still weak-limbed and weak-hearted, until he he grows and his strength firms, his limbs become vigorous, his bones fill with marrow and he can endure the exertion of study, and that the illness of fainting [spells] not happen to him on account of much exertion upon it. However after his strength firms and his eyes enlighten to understand the voice of his teachers, then is the thing proper and fit; and he is [then] obligated to put his neck to the yoke of Torah [study], and not to loosen it from him, even a hair’s breadth. And he should [then] always give him to drink from its spiced wine, and feed him from its honey. And also from the content of the commandment is that which they, may their memory be blessed, said (Kiddushin 30a), “To what extent is a man obligated to teach his son Torah? Rav Yehudah says that Shmuel said, ‘[Like], for example, Zevulun ben Dan.’” The understanding of [this is that there was] a man in their generation whose name was Zevulun ben Dan, whose father’s father taught him Scripture, Mishnah, Talmud, laws, and homilies (aggadot). And they challenged what they challenged about this in the Gemara, and the resolution was that the obligation is to teach him Scripture — which is Torah — like the father’s father of Zevulun did, and even though the father’s father of Zevulun ben Dan taught him more. And one who adds upon the obligation of the commandment, like the father’s father of Zevulun ben Dan, brings a blessing upon himself. And one who was not taught by his fathers who are obligated in this — such as his father and his father’s father — is obligated to teach himself when he is an adult and recognizes the matter, as it is stated (Deuteronomy 5:1), “and study them and do them.” And if [both] the father and the son needed to study, and the father does not have [enough] in his hand that they can both study, he always [comes] before his son. But if his son is more understanding than he and his [son’s] studies are more [effective], his son precedes him. And until when is every man obligated to study Torah? Until the day of his death, as it is stated (Deuteronomy 4:9), “and lest they be diverted from your heart, all of the days of your life” (Mishneh Torah, Laws of Torah Study 1:10). And the Sages emphasized the matter more by way of ethics and to teach people desire [for it] and said (Shabbat 83b) that even at the time of death, a man is obligated to study Torah, as it is stated (Numbers 19:14), “This is the law of the Torah, when a man dies in a tent.” And everyone in Israel is obligated in the study of Torah (Yoma 35b) — whether poor or rich, whether healthy or one with afflictions. And they, may their memory be blessed, already said (Eruvin 54a) that all of the limbs are healed by involvement in Torah. And even a poor person that goes around to [other people’s] doors, and even a married man with children — everyone — is obligated to set time for Torah [study] during the day and during the night, as it is stated (Joshua 1:8), “and you shall meditate in it day and night.”