לֹא־תֹאכַ֤ל עָלָיו֙ חָמֵ֔ץ שִׁבְעַ֥ת יָמִ֛ים תֹּֽאכַל־עָלָ֥יו מַצּ֖וֹת לֶ֣חֶם עֹ֑נִי כִּ֣י בְחִפָּז֗וֹן יָצָ֙אתָ֙ מֵאֶ֣רֶץ מִצְרַ֔יִם לְמַ֣עַן תִּזְכֹּר֔ אֶת־י֤וֹם צֵֽאתְךָ֙ מֵאֶ֣רֶץ מִצְרַ֔יִם כֹּ֖ל יְמֵ֥י חַיֶּֽיךָ׃
Thou shalt eat no leavened bread with it; seven days shalt thou eat unleavened bread therewith, even the bread of affliction; for in haste didst thou come forth out of the land of Egypt; that thou mayest remember the day when thou camest forth out of the land of Egypt all the days of thy life.
Rashi on Deuteronomy
לחם עני THE BREAD OF AFFLICTION — i.e. bread that calls to mind the affliction to which they were subjected in Egypt (Sifrei Devarim 130:5).
Sforno on Deuteronomy
לא תאכל עליו חמץ שבעת ימים, even though in Egypt the prohibition of eating chametz was in effect for only one day, as our sages pointed out in Pessachim 96.
Rabbeinu Bahya
לא תאכל עליו חמץ, “Do not eat any leavened matter with it.” This refers already to the time when the Passover sacrifice may be slaughtered, i.e. about midday. At that time one must no longer own anything leavened (Ibn Ezra).