Exodus 12:7-13

Moreover, they shall take some of the blood and put it on the two doorposts and on the lintel of the houses in which they eat it. They shall eat the flesh that same night, roasted with fire, and they shall eat it with unleavened bread and bitter herbs. Do not eat any of it raw or boiled at all with water, but rather roasted with fire, both its head and its legs along with its entrails. And you shall not leave any of it over until morning, but whatever is left of it until morning, you shall completely burn with fire. Now you shall eat it in this way: with your garment belted around your waist, your sandals on your feet, and your staff in your hand; and you shall eat it in a hurry—it is the LORD’S Passover. For I will go through the land of Egypt on that night, and fatally strike all the firstborn in the land of Egypt, from the human firstborn to animals; and against all the gods of Egypt I will execute judgments—I am the LORD. The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will come upon you to destroy you when I strike the land of Egypt.