Exodus 11:5-10

11:5 and all the firstborn in the land of Egypt will die, from the firstborn son of Pharaoh who sits on his throne, to the firstborn son of the slave girl who is at her hand mill, and all the firstborn of the cattle. 11:6 There will be a great cry throughout the whole land of Egypt, such as there has never been, nor ever will be again. 11:7 But against any of the Israelites not even a dog will bark against either people or animals, so that you may know that the Lord distinguishes between Egypt and Israel.’ 11:8 All these your servants will come down to me and bow down to me, saying, ‘Go, you and all the people who follow you,’ and after that I will go out.” Then Moses went out from Pharaoh in great anger.

11:9 The Lord said to Moses, “Pharaoh will not listen to you, so that my wonders may be multiplied in the land of Egypt.”

11:10 So Moses and Aaron did all these wonders before Pharaoh, but the Lord hardened Pharaoh’s heart, and he did not release the Israelites from his land.