Exodus 12:11-14

This is how you shall eat it: your loins girded, your sandals on your feet, and your staff in your hand; and you shall eat it hurriedly. It is the passover of the LORD. 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 judgments: I am the LORD. 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. 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.