Exodus 10:21-22
The Ninth Blow: Darkness
10:21 The Lord said to Moses, “Extend your hand toward heaven so that there may be darkness over the land of Egypt, a darkness so thick it can be felt.”
10:22 So Moses extended his hand toward heaven, and there was absolute darkness throughout the land of Egypt for three days.
Exodus 14:20
14:20 It came between the Egyptian camp and the Israelite camp; it was a dark cloud
and it lit up the night so that one camp did not come near the other
the whole night.