Exodus 11:5; Exodus 12:29; Exodus 17:16

5 and all the firstborn in the land of Egypt shall die, from the firstborn of the Pharaoh who sits on his throne, even to the firstborn of the slave girl who is behind the millstones; all the firstborn of the cattle as well.

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.

16 and he said, "The LORD has sworn ; the LORD will have war against Amalek from generation to generation."