For I will go through the land of Egypt in that night, and will strike all the firstborn in the land of Egypt, both man and animal. Against all the gods of Egypt I will execute judgments: I am the LORD.
and it happened, when Par`oh would hardly let us go, that the LORD killed all the firstborn in the land of Egypt, both the firstborn of man, and the firstborn of animal. Therefore I sacrifice to the LORD all that opens the womb, being males; but all the firstborn of my sons I redeem.'