Exodus 12:12-15

“That night I will go through the land of Egypt and kill all the firstborn animals and people in the land of Egypt. I will also punish all the gods of Egypt. I am the LORD. But the blood will be a sign on the houses where you are. When I see the blood, I will pass over you. Nothing terrible will hurt you when I punish the land of Egypt. “You are always to remember this day and celebrate it with a feast to the LORD. Your descendants are to honor the LORD with this feast from now on. For this feast you must eat bread made without yeast for seven days. On the first day, you are to remove all the yeast from your houses. No one should eat any yeast for the full seven days of the feast, or that person will be cut off from Israel.