Exodus 10:21-26

Then the LORD said to Moses, “Stretch out your hand toward heaven, that there may be darkness over the land of Egypt, darkness which may even be felt.” So Moses stretched out his hand toward heaven, and there was thick darkness in all the land of Egypt three days. They did not see one another; nor did anyone rise from his place for three days. But all the children of Israel had light in their dwellings. Then Pharaoh called to Moses and said, “Go, serve the LORD; only let your flocks and your herds be kept back. Let your little ones also go with you.” But Moses said, “You must also give us sacrifices and burnt offerings, that we may sacrifice to the LORD our God. Our livestock also shall go with us; not a hoof shall be left behind. For we must take some of them to serve the LORD our God, and even we do not know with what we must serve the LORD until we arrive there.”