Exodus 12:22-24

New Revised Standard Version, Anglicised Catholic Edition

²² Take a bunch of hyssop, dip it in the blood that is in the basin, and touch the lintel and the two doorposts with the blood in the basin. None of you shall go outside the door of your house until morning. ²³ For the Lord will pass through to strike down the Egyptians; when he sees the blood on the lintel and on the two doorposts, the Lord will pass over that door and will not allow the destroyer to enter your houses to strike you down. ²⁴ You shall observe this rite as a perpetual ordinance for you and your children.