Exodus 12:23-25

Complete Jewish Bible

²³ For Adonai will pass through to kill the Egyptians; but when he sees the blood on the top and on the two sides, Adonai will pass over the door and will not allow the Slaughterer to enter your houses and kill you. ²⁴ You are to observe this as a law, you and your descendants forever.

²⁵ “When you come to the land which Adonai will give you, as he has promised, you are to observe this ceremony.