This chapter founds Passover, in Hebrew Pesach, the spring feast that remembers the night God struck Egypt's firstborn and passed over the blood-marked houses. Jewish families keep it to this day with a ceremonial meal called the seder (Hebrew for “order”): unleavened flatbread (matzah), bitter herbs, cups of wine, and the retelling of this chapter's story, with the children asking the questions.

Honesty about the timeline helps the reader: in the Bible's own period the center of the feast was the lamb, slain and eaten as this chapter commands. The seder as now practiced took its shape after the Temple fell in AD 70 and the lamb could no longer be offered; its oldest written outline is in the Mishnah, the first code of Jewish oral law (about AD 200), which already includes the four cups and the rule that “in every generation a person must see himself as if he personally came out of Egypt.”