(ה) רַבָּן גַּמְלִיאֵל הָיָה אוֹמֵר, כָּל שֶׁלֹּא אָמַר שְׁלֹשָׁה דְבָרִים אֵלּוּ בְּפֶסַח, לֹא יָצָא יְדֵי חוֹבָתוֹ, וְאֵלּוּ הֵן, פֶּסַח, מַצָּה, וּמָרוֹר. פֶּסַח, עַל שׁוּם שֶׁפָּסַח הַמָּקוֹם עַל בָּתֵּי אֲבוֹתֵינוּ בְמִצְרַיִם. מַצָּה, עַל שׁוּם שֶׁנִּגְאֲלוּ אֲבוֹתֵינוּ בְמִצְרַיִם. מָרוֹר, עַל שׁוּם שֶׁמֵּרְרוּ הַמִּצְרִים אֶת חַיֵּי אֲבוֹתֵינוּ בְמִצְרָיִם. בְּכָל דּוֹר וָדוֹר חַיָּב אָדָם לִרְאוֹת אֶת עַצְמוֹ כְאִלּוּ הוּא יָצָא מִמִּצְרַיִם, שֶׁנֶּאֱמַר (שמות יג), וְהִגַּדְתָּ לְבִנְךָ בַּיּוֹם הַהוּא לֵאמֹר, בַּעֲבוּר זֶה עָשָׂה ה' לִי בְּצֵאתִי מִמִּצְרָיִם. לְפִיכָךְ אֲנַחְנוּ חַיָּבִין לְהוֹדוֹת, לְהַלֵּל, לְשַׁבֵּחַ, לְפָאֵר, לְרוֹמֵם, לְהַדֵּר, לְבָרֵךְ, לְעַלֵּה, וּלְקַלֵּס, לְמִי שֶׁעָשָׂה לַאֲבוֹתֵינוּ וְלָנוּ אֶת כָּל הַנִּסִּים הָאֵלּוּ, הוֹצִיאָנוּ מֵעַבְדוּת לְחֵרוּת, מִיָּגוֹן לְשִׂמְחָה, וּמֵאֵבֶל לְיוֹם טוֹב, וּמֵאֲפֵלָה לְאוֹר גָּדוֹל, וּמִשִּׁעְבּוּד לִגְאֻלָּה. וְנֹאמַר לְפָנָיו, הַלְלוּיָהּ:
(5) Rabban Gamliel used to say: Whoever does not mentioned these three things on Passover does not discharge his duty, and these are they: the Passover-offering, unleavened bread, and bitter herbs. [The] Passover-offering [is offered] because the Omnipresent One passed over the houses of our ancestors in Egypt. Unleavened bread [is eaten] because our ancestors were redeemed from Egypt. [The] bitter herb is [eaten] because the Egyptians embittered the lives of our ancestors in Egypt. In every generation a person must regard himself as though he personally had gone out of Egypt, as it is said: “And you shall tell your son in that day, saying: ‘It is because of what the Lord did for me when I came forth out of Egypt.’” Therefore it is our duty to thank, praise, laud, glorify, exalt, honor, bless, extol, and adore Him Who performed all these miracles for our ancestors and us; He brought us forth from bondage into freedom, from sorrow into joy, from mourning into festivity, from darkness into great light, and from servitude into redemption. Therefore let us say before Him, Hallelujah!
Rabbi Joseph Dov Soloveitchik, Festival of Freedom: Essays on Pesach and the Haggadah
The standard text reads, “In each generation, one is duty-bound lirot et atzmo, to consider himself, as if he had been delivered from Egyptian bondage.” Instead of the reflexive verb lirot et atzmo, signifying an inner experience, Maimonides substitutes the verb, l’harot et atzmo, to demonstrate, to behave in a manner manifesting the experience of finding liberty after having been enslaved for a long time.English