Moses and Aaron performed all these wonders before Pharaoh, but the Lord hardened Pharaoh’s heart, and he would not let the Israelites go out of his land.
When Pharaoh stubbornly refused to let us go, the Lord killed all the firstborn in the land of Egypt, from human firstborn to the firstborn of animals. Therefore I sacrifice to the Lord every male that first opens the womb, but every firstborn of my sons I redeem.’
And the Lord said to Moses, “When you go back to Egypt, see that you perform before Pharaoh all the wonders that I have put in your power, but I will harden his heart, so that he will not let the people go.
Then the Lord said to Moses, “Now you shall see what I will do to Pharaoh: indeed, by a mighty hand he will let them go; by a mighty hand he will drive them out of his land.”
Pharaoh inquired and found that not even one of the Israelites’ livestock had died. But the heart of Pharaoh was hardened, and he would not let the people go.