Exodus 8:23 akjv — And I will put a division between my people and your people: to morrow shall this sign be.

And the LORD said to Moses, Rise up early in the morning, and stand before Pharaoh; see, he comes forth to the water; and say to him, Thus says the LORD, Let my people go, that they may serve me.

Else, if you will not let my people go, behold, I will send swarms of flies on you, and on your servants, and on your people, and into your houses: and the houses of the Egyptians shall be full of swarms of flies, and also the ground where on they are.

And I will sever in that day the land of Goshen, in which my people dwell, that no swarms of flies shall be there; to the end you may know that I am the LORD in the middle of the earth.

And the LORD did so; and there came a grievous swarm of flies into the house of Pharaoh, and into his servants’ houses, and into all the land of Egypt: the land was corrupted by reason of the swarm of flies. ¶

And Pharaoh called for Moses and for Aaron, and said, Go you, sacrifice to your God in the land.

And Moses said, It is not meet so to do; for we shall sacrifice the abomination of the Egyptians to the LORD our God: see, shall we sacrifice the abomination of the Egyptians before their eyes, and will they not stone us?