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 doorframe. Not one of you shall go out the door of his house until morning. When the LORD goes through the land to strike down the Egyptians, he will see the blood on the top and sides of the doorframe and will pass over that doorway, and he will not permit the destroyer to enter your houses and strike you down. "Obey these instructions as a lasting ordinance for you and your descendants. (Exodus 12:22-24 NIV)