Exodus 11:4-7

4So Moses said, “This is what Adonai says: At around midnight I will go out into the midst of Egypt,

5and all the firstborn in the land of Egypt will die—from the firstborn of Pharaoh sitting on his throne to the firstborn of the maidservant behind the mill, along with all the firstborn cattle.

6There will be a great cry throughout all the land of Egypt, the likes of which has never been before nor will ever be again.

7But not so much as a dog will growl against any of Bnei-Yisrael, neither man nor beast—so that you may know that Adonai makes a distinction between the Egyptians and Israel.