Moses and Aaron did all these wonders before Pharaoh; and the Lord hardened Pharaoh's heart, and he did not let the people of Israel go out of his land.
For when Pharaoh stubbornly refused to let us go, the Lord slew all the first-born in the land of Egypt, both the first-born of man and the first-born of cattle. Therefore I sacrifice to the Lord all the males that first open the womb; but all the first-born of my sons I redeem.’
And the Lord said to Moses, “When you go back to Egypt, see that you do before Pharaoh all the miracles which I have put in your power; but I will harden his heart, so that he will not let the people go.
But the Lord said to Moses, “Now you shall see what I will do to Pharaoh; for with a strong hand he will send them out, yea, with a strong hand he will drive them out of his land.”
And Pharaoh sent, and behold, not one of the cattle of the Israelites was dead. But the heart of Pharaoh was hardened, and he did not let the people go.