Exodus 10:20 in the World English Bible
But the LORD hardened Pharaoh’s heart, and he didn’t let the children of Israel go.
Context
19 And 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.
20 But the LORD hardened Pharaoh’s heart, so that he would not let the children of Israel go.
21 And the LORD said unto Moses, Stretch out thine hand toward heaven, that there may be darkness over the land of Egypt, even darkness which may be felt.