Exodus 12:22-24

Modern English Version

²² You shall take a bunch of hyssop, and dip it in the blood that is in the basin, and apply the lintel and the two side posts with the blood that is in the basin, and none of you shall go out from the door of his house until the morning. ²³ For the Lord will pass through to kill the Egyptians. And when He sees the blood upon the lintel and on the two side posts, the Lord will pass over the door and will not permit the destroyer to come to your houses to kill you.

²⁴ “And you shall observe this thing as an ordinance to you and to your sons forever.