Moses and Aaron did all these wonders before Pharaoh, and the LORD hardened Pharaoh's heart, and he did not let the people of Israel go out of his land.

The LORD said to Moses and Aaron in the land of Egypt, “This month shall be for you the beginning of months. It shall be the first month of the year for you. Tell all the congregation of Israel that on the tenth day of this month every man shall take a lamb according to their fathers' houses, a lamb for a household. And if the household is too small for a lamb, then he and his nearest neighbor shall take according to the number of persons; according to what each can eat you shall make your count for the lamb. Your lamb shall be without blemish, a male a year old. You may take it from the sheep or from the goats, and you shall keep it until the fourteenth day of this month, when the whole assembly of the congregation of Israel shall kill their lambs at twilight.

“Then they shall take some of the blood and put it on the two doorposts and the lintel of the houses in which they eat it. They shall eat the flesh that night, roasted on the fire; with unleavened bread and bitter herbs they shall eat it. Do not eat any of it raw or boiled in water, but roasted, its head with its legs and its inner parts. And you shall let none of it remain until the morning; anything that remains until the morning you shall burn. In this manner you shall eat it: with your belt fastened, your sandals on your feet, and your staff in your hand. And you shall eat it in haste. It is the LORD's Passover. For I will pass through the land of Egypt that night, and I will strike all the firstborn in the land of Egypt, both man and beast; and on 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 are. And when I see the blood, I will pass over you, and no plague will befall you to destroy you, when I strike the land of Egypt.

“This day shall be for you a memorial day, and you shall keep it as a feast to the LORD; throughout your generations, as a statute forever, you shall keep it as a feast.

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At midnight the LORD struck down all the firstborn in the land of Egypt, from the firstborn of Pharaoh who sat on his throne to the firstborn of the captive who was in the dungeon, and all the firstborn of the livestock. And Pharaoh rose up in the night, he and all his servants and all the Egyptians. And there was a great cry in Egypt, for there was not a house where someone was not dead. Then he summoned Moses and Aaron by night and said, “Up, go out from among my people, both you and the people of Israel; and go, serve the LORD, as you have said. Take your flocks and your herds, as you have said, and be gone, and bless me also!”

(Exodus 11:10-12:14; 12:29-32 ESV)