Exodus 12:22-24

Revised Standard Version

²² Take a bunch of hyssop and dip it in the blood which is in the basin, and touch the lintel and the two doorposts with the blood which is in the basin; and none of you shall go out of the door of his house until the morning. ²³ For the Lord will pass through to slay the Egyptians; and when he sees the blood on the lintel and on the two doorposts, the Lord will pass over the door, and will not allow the destroyer to enter your houses to slay you. ²⁴ You shall observe this rite as an ordinance for you and for your sons for ever.