Exodus 10:21-23

And Yahweh said to Moses, “Stretch out your hand toward the heavens so that there may be darkness over the land of Egypt and so that a person can feel darkness.” And Moses stretched out his hand toward the heavens, and there was darkness of night in all the land of Egypt for three days. No one could see his brother, and because of it no one could move from where they were for three days, but there was light for the Israelites in their dwellings.