The Chinuch explains the deep rationale for honoring parents: a person must acknowledge those who brought them into being and raised them. He draws an analogy to gratitude toward God, arguing that someone ungrateful to parents will inevitably be ungrateful to God. The mitzvah thus trains the character for all religious life.
מִצְוַת כִּבּוּד אָב וָאֵם – לְכַבֵּד הָאָב וְהָאֵם, שֶׁנֶּאֱמַר (שמות כ יב) כַּבֵּד אֶת אָבִיךָ וְאֶת אִמֶּךָ וְגוֹ'. וּבָא הַפֵּרוּשׁ (קדושין לא, ב) אֵי זֶהוּ כִּבּוּד, מַאֲכִיל וּמַשְׁקֶה מַלְבִּישׁ וּמְכַסֶּה מַכְנִיס וּמוֹצִיא. מִשָּׁרְשֵׁי מִצְוָה זוֹ, שֶׁרָאוּי לוֹ לָאָדָם שֶׁיַּכִּיר וְיִגְמֹל חֶסֶד לְמִי שֶׁעָשָׂה עִמּוֹ טוֹבָה, וְלֹא יִהְיֶה נָבָל וּמִתְנַכֵּר וּכְפוּי טוֹבָה שֶׁזּוֹ מִדָּה רָעָה וּמְאוּסָה בְּתַכְלִית לִפְנֵי אֱלֹהִים וַאֲנָשִׁים. וְשֶׁיִּתֵּן אֶל לִבּוֹ כִּי הָאָב וְהָאֵם הֵם סִבַּת הֱיוֹתוֹ בָּעוֹלָם, וְעַל כֵּן בֶּאֱמֶת רָאוּי לוֹ לַעֲשׂוֹת לָהֶם כָּל כָּבוֹד וְכָל תּוֹעֶלֶת שֶׁיּוּכַל, כִּי הֵם הֱבִיאוּהוּ לָעוֹלָם, גַּם יָגְעוּ בּוֹ כַּמָּה יְגִיעוֹת בְּקַטְנוּתוֹ, וּכְשֶׁיִּקְבַּע זֹאת הַמִּדָּה בְּנַפְשׁוֹ יַעֲלֶה מִמֶּנָּה לְהַכִּיר טוֹבַת הָאֵל בָּרוּךְ הוּא שֶׁהוּא סִבָּתוֹ וְסִבַּת כָּל אֲבוֹתָיו עַד אָדָם הָרִאשׁוֹן, וְשֶׁהוֹצִיאוֹ לַאֲוִיר הָעוֹלָם וְסִפֵּק צָרְכּוֹ כָּל יָמָיו וְהֶעֱמִידוֹ עַל מַתְכֻּנְתּוֹ וּשְׁלֵמוּת אֵבָרָיו, וְנָתַן בּוֹ נֶפֶשׁ יוֹדַעַת וּמַשְׂכֶּלֶת, שֶׁאִלּוּלֵי הַנֶּפֶשׁ שֶׁחֲנָנוֹ הָאֵל, יִהְיֶה כְּסוּס כְּפֶרֶד אֵין הָבִין, וְיַעֲרִיךְ בְּמַחְשַׁבְתּוֹ כַּמָּה וְכַמָּה רָאוּי לְהִזָּהֵר בַּעֲבוֹדָתוֹ בָּרוּךְ הוּא.
The commandment to honor father and mother: To honor father and mother, as it is stated (Exodus 20:12), “You shall honor your father and your mother.” And the explanation (Kiddushin 31b) comes to [define it], “What does it mean to ‘honor’? To feed, give drink, dress, bring in, and take out.” From the roots of this commandment is that it is fitting for a person to acknowledge and return kindness to people who were good to him, and not to be an ungrateful scoundrel, because that is a bad and repulsive attribute before God and people. And he should take to heart that the father and the mother are the cause of his being in the world; and hence it is truly fitting to honor them in every way and give every benefit he can to them, because they brought him to the world, and worked hard for him when he was little. And once he fixes this idea in his soul, he will move up from it to recognize the good of God, blessed be He, Who is his cause and the cause of all his ancestors until the first man (Adam), and that He took him out into the world’s air, and fulfilled his needs every day, and made his body strong and able to stand, and gave him a mind that knows and learns — for without the mind that God granted him, he would be “like a horse or a mule who does not understand.” And he should think at length about how very fitting it is to be careful in his worship of the Blessed be He.