Moses and Aaron did all these wonders before Pharaoh, but the LORD hardened Pharaoh’s heart so that he would not let the Israelites go out of his land.
Jewish Publication Society of America Version (JPS1917) - Exodus 11:10 >And 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.