Exodus 12:3; 7; 12-13; 29-30
3 Speak to all the congregation of Israel, saying, ‘On the tenth of this month they are each one to take a lamb for themselves, according to their fathers’ households, a lamb for each household.

7 Moreover, they shall take some of the blood and put it on the two doorposts and on the lintel of the houses in which they eat it.

12 For I will go through the land of Egypt on that night, and will strike down all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgments – I am the Lord.
13 The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will befall you to destroy you when I strike the land of Egypt.

29 Now it came about at midnight that the Lord struck all the firstborn in the land of Egypt, from the firstborn of Pharaoh who sat on his throne to the firstborn of the captive who was in the dungeon, and all the firstborn of cattle.
30 Pharaoh arose in the night, he and all his servants and all the Egyptians, and there was a great cry in Egypt, for there was no home where there was not someone dead.