Exodus 11:4-7

Moses said, “Thus says the LORD, ‘About midnight I am going out into the midst of Egypt, 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. Moreover, there shall be a great cry in all the land of Egypt, such as there has not been before and such as shall never be again. But against any of the sons of Israel a dog will not even bark, whether against man or beast, that you may understand how the LORD makes a distinction between Egypt and Israel.’