Exodus 8:16-23

Then the LORD said to Moses, “Tell Aaron, ‘Stretch out your staff and strike the dust of the ground,’ and throughout the land of Egypt the dust will become gnats.” They did this, and when Aaron stretched out his hand with the staff and struck the dust of the ground, gnats came on people and animals. All the dust throughout the land of Egypt became gnats. But when the magicians tried to produce gnats by their secret arts, they could not. Since the gnats were on people and animals everywhere, the magicians said to Pharaoh, “This is the finger of God.” But Pharaoh’s heart was hard and he would not listen, just as the LORD had said. Then the LORD said to Moses, “Get up early in the morning and confront Pharaoh as he goes to the river and say to him, ‘This is what the LORD says: Let my people go, so that they may worship me. If you do not let my people go, I will send swarms of flies on you and your officials, on your people and into your houses. The houses of the Egyptians will be full of flies; even the ground will be covered with them. “ ‘But on that day I will deal differently with the land of Goshen, where my people live; no swarms of flies will be there, so that you will know that I, the LORD, am in this land. I will make a distinction between my people and your people. This sign will occur tomorrow.’ ”