On the opening of the Ten Commandments, Ramban emphasizes that the Exodus is the foundation of faith because it reveals God’s intervention in history and establishes belief in hidden providence behind later events.
אָנֹכִי ה' אֱלֹהֶיךָ הַדִּבּוּר הַזֶּה מִצְוַת עֲשֵׂה, אָמַר אָנֹכִי ה', יוֹרֶה וִיצַוֶּה אוֹתָם שֶׁיֵּדְעוּ וְיַאֲמִינוּ כִּי יֵשׁ ה', וְהוּא אֱלֹהִים לָהֶם, כְּלוֹמַר הוֹוֶה, קַדְמוֹן, מֵאִתּוֹ הָיָה הַכֹּל בְּחֵפֶץ וִיכֹלֶת, וְהוּא אֱלֹהִים לָהֶם, שֶׁחַיָּבִים לַעֲבֹד אוֹתוֹ. וְאָמַר אֲשֶׁר הוֹצֵאתִיךָ מֵאֶרֶץ מִצְרַיִם, כִּי הוֹצָאָתָם מִשָּׁם תּוֹרֶה עַל הַמְּצִיאוּת וְעַל הַחֵפֶץ, כִּי בִּידִיעָה וּבְהַשְׁגָּחָה מִמֶּנּוּ יָצָאנוּ מִשָּׁם, וְגַם תּוֹרֶה עַל הַחִדּוּשׁ, כִּי עִם קַדְמוּת הָעוֹלָם לֹא יִשְׁתַּנֶּה דָּבָר מִטִּבְעוֹ, וְתוֹרֶה עַל הַיְּכֹלֶת, וְהַיְּכֹלֶת תּוֹרֶה עַל הַיִּחוּד, כְּמוֹ שֶׁאָמַר (שמות ט':י"ד) "בַּעֲבוּר תֵּדַע כִּי אֵין כָּמֹנִי בְּכָל הָאָרֶץ". וְזֶה טַעַם "אֲשֶׁר הוֹצֵאתִיךָ", כִּי הֵם הַיּוֹדְעִים וְעֵדִים בְּכָל אֵלֶּה:
I AM THE ETERNAL THY G-D. This Divine utterance constitutes a positive commandment. He said, I am the Eternal, thus teaching and commanding them that they should know and believe that the Eternal exists and that He is G-d to them. That is to say, there exists an Eternal Being through Whom everything has come into existence by His will and power, and He is G-d to them, who are obligated to worship Him. He said, Who brought thee out of the land of Egypt, because His taking them out from there was the evidence establishing the existence and will of G-d, for it was with His knowledge and providence that we came out from there. The exodus is also evidence for the creation of the world, for assuming the eternity of the universe, [which precludes a Master of the universe Who is in control of it], it would follow that nothing could be changed from its nature. And it is also evidence for G-d’s infinite power, and His infinite power is an indication of the Unity, as He said, that thou [i.e., Pharaoh] mayest know that there is none like Me in all the earth. This is the intent of the expression, Who brought thee out, since they are the ones who know and are witnesses to all these things.