Exodus 10:21 in the King James Version
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.
Context
20 But the LORD hardened Pharaoh’s heart, and he didn’t let the children of Israel go.
21 The LORD said to Moses, “Stretch out your hand toward the sky, that there may be darkness over the land of Egypt, even darkness which may be felt.”
22 Moses stretched out his hand toward the sky, and there was a thick darkness in all the land of Egypt for three days.