Exodus 10:21-23

21Then the Lord said to Moses, “1Reach out with your hand toward the sky, so that there may be darkness over the land of Egypt, even a darkness 2which may be felt.”

22So Moses reached out with his hand toward the sky, and there was 3thick darkness in all the land of Egypt for three days.

23They did not see one another, nor did anyone rise from his place for three days, 4but all the sons of Israel had light in their dwellings.