Exodus 11:4-10 NKJV
Then Moses said, “Thus says the LORD: ‘About midnight I will go out into the midst of Egypt; and 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. Then 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. But 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.’ And all these your servants shall come down to me and bow down to me, saying, ‘Get out, and all the people who follow you!’ After that I will go out.” Then he went out from Pharaoh in great anger.
But the LORD said to Moses, “Pharaoh will not heed you, so that My wonders may be multiplied in the land of Egypt.” So Moses and Aaron did all these wonders before Pharaoh; and the LORD hardened Pharaoh’s heart, and he did not let the children of Israel go out of his land.
NKJV: New King James Version