Exodus 12:21-23

New International Version - UK

²¹ Then Moses summoned all the elders of Israel and said to them, ‘Go at once and select the animals for your families and slaughter the Passover lamb. ²² Take a bunch of hyssop, dip it into the blood in the basin and put some of the blood on the top and on both sides of the door-frame. None of you shall go out of the door of your house until morning. ²³ When the Lord goes through the land to strike down the Egyptians, he will see the blood on the top and sides of the door-frame and will pass over that doorway, and he will not permit the destroyer to enter your houses and strike you down.