Exodus 10:20
King James Version
“But the LORD hardened Pharaoh’s heart, so that he would not let the children of Israel go.”
Context
17Now therefore forgive, I pray thee, my sin only this once, and intreat the LORD your God, that he may take away from me this death only.
18And he went out from Pharaoh, and intreated the LORD.
19And the LORD turned a mighty strong west wind, which took away the locusts, and cast them into the Red sea; there remained not one locust in all the coasts of Egypt.
20But the LORD hardened Pharaoh’s heart, so that he would not let the children of Israel go.
21And the LORD said unto Moses, Stretch out thine hand toward heaven, that there may be darkness over the land of Egypt, even darkness may be felt.
22And Moses stretched forth his hand toward heaven; and there was a thick darkness in all the land of Egypt three days:
23They saw not one another, neither rose any from his place for three days: but all the children of Israel had light in their dwellings.