Exodus 11:4-7

4Then Moses said, “Thus says the Lord: ‘About midnight I will go out into the midst of Egypt;

5and all the firstborn in the land of Egypt shall die, from the firstborn of Pharaoh who sits on his throne, even to the firstborn of the female servant who is behind the handmill, and all the firstborn of the animals.

6Then there shall be a great cry throughout all the land of Egypt, such as was not like it before, nor shall be like it again.

7But against none of the children of Israel shall a dog move its tongue, against man or beast, that you may know that the Lord does make a difference between the Egyptians and Israel.’