Exodus 10:21-23

Young's Literal Translation

²¹ And Jehovah saith unto Moses, `Stretch out thy hand towards the heavens, and there is darkness over the land of Egypt, and the darkness is felt.'

²² And Moses stretcheth out his hand towards the heavens, and there is darkness -- thick darkness in all the land of Egypt three days;

²³ they have not seen one another, and none hath risen from his place three days; and to all the sons of Israel there hath been light in their dwellings.'