קל"ה, הלכות פסח : א
The Exodus from Egypt is related to the revelation of da'as, from which come three effects: the well, the cloud, and the mahn. These items correspond to the acts of eating, drinking, and dress. And, these items relate to the three mitzvos done at the seder, for matzah relates to a persons brain and da'as. It is through da'as that one merits to wage war against Amalek. He also merits the concept of tikkun habris and the holiness of Shabbos, which relates to the idea of completely nullifying evil. All of these aforementioned concepts are hinted to by every aspect of the Pesach seder and the mitzvah of Counting the Omer after the first day of Pesach.