Exodus 12:7, 11-12

And they shall take of the blood, and strike it on the two side posts and on the upper door post of the houses, wherein they shall eat it.

And thus shall ye eat it; with your loins girded, your shoes on your feet, and your staff in your hand; and ye shall eat it in haste: it is the LORD's passover. For I will pass through the land of Egypt this night, and will smite all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the LORD.