Exodus 11:4-6

4Then Moses said, “This is what the Lord says: ‘About 1midnight I am going out into the midst of Egypt,

5and 2all the firstborn in the land of Egypt shall die, from the firstborn of the Pharaoh who sits on his throne, to the firstborn of the slave girl who is behind the millstones; all the firstborn of the cattle as well.

6So there shall be 3a great cry in all the land of Egypt, such as there has not been before and such as shall never be again.