Exodus 10:21-23

²¹Yahweh 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." ²²Moses stretched forth his hand toward the sky, and there was a thick darkness in all the land of Egypt three days. ²³They didn`t see one another, neither did anyone rise from his place for three days; but all the children of Israel had light in their dwellings.