Exodus 12:12-14

New Revised Standard Version, Anglicised

¹² For I will pass through the land of Egypt that night, and I will strike down every firstborn in the land of Egypt, both human beings and animals; on all the gods of Egypt I will execute judgements: I am the Lord. ¹³ The blood shall be a sign for you on the houses where you live: when I see the blood, I will pass over you, and no plague shall destroy you when I strike the land of Egypt.

¹⁴ This day shall be a day of remembrance for you. You shall celebrate it as a festival to the Lord; throughout your generations you shall observe it as a perpetual ordinance.