Exodus 12:21-12:28

Moses then summoned all the elders of Israel and said to them, "Go, pick out lambs for your families, and slaughter the passover offering. Take a bunch of hyssop, dip it in the blood that is in the basin, and apply some of the blood that is in the basin to the lintel and to the two doorposts. None of you shall go outside the door of his house until morning. For when the Lord goes through to smite the Egyptians, He will see the blood on the lintel and the two doorposts, and the Lord will pass over the door and not let the Destroyer enter and smite your home. "You shall observe this as an institution for all time, for you and for your descendants. And when you enter the land that the Lord will give you, as He has promised, you shall observe this rite. And when your children ask you, 'What do you mean by this rite?' you shall say, 'It is the passover sacrifice to the Lord, because He passed over the houses of the Israelites in Egypt when He smote the Egyptians, but saved our houses.'" The people then bowed low in homage. And the Israelites went and did so; just as the Lord had commanded Moses and Aaron, so they did.