Exodus 12:24-30

And you shall observe this event as an ordinance for you and your children forever. When you enter the land which the LORD will give you, as He has promised, you shall observe this rite. And when your children say to you, ‘What does this rite mean to you?’ you shall say, ‘It is a Passover sacrifice to the LORD who passed over the houses of the sons of Israel in Egypt when He smote the Egyptians, but spared our homes.’ ” And the people bowed low and worshiped. Then the sons of Israel went and did so; just as the LORD had commanded Moses and Aaron, so they did. Now it came about at midnight that the LORD struck 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 cattle. Pharaoh arose in the night, he and all his servants and all the Egyptians, and there was a great cry in Egypt, for there was no home where there was not someone dead.