Exodus 11:5-7

Every firstborn son in the land of Egypt will die—from the firstborn son of the king, who sits on his throne, to the firstborn of the slave girl grinding grain. Also the firstborn farm animals will die. There will be loud outcries everywhere in Egypt, worse than any time before or after this. But not even a dog will bark at the Israelites or their animals.’ Then you will know that the LORD treats Israel differently from Egypt.