Exodus 8, 16 – 20 „Then the LORD spoke to Moses: Early tomorrow morning present yourself to Pharaoh when he sets out toward the water, and say to him: Thus says the LORD: Let my people go to serve me. 17For if you do not let my people go, I will send swarms of flies upon you and your servants and your people and your houses. The houses of the Egyptians and the very ground on which they stand will be filled with swarms of flies. 18But on that day I will make an exception of the land of Goshen, where my people are, and no swarms of flies will be there, so that you may know that I the LORD am in the midst of the land. 19I will make a distinction between my people and your people. This sign will take place tomorrow. 20This the LORD did. Thick swarms of flies entered the house of Pharaoh and the houses of his servants; throughout Egypt the land was devastated on account of the swarms of flies”.