Exodus 8:20-27

20And Jehovah said to Moses, Rise up early in the morning, and stand before Pharaoh — behold, he will go out to the water — and say to him, Thus saith Jehovah, Let my people go, that they may serve me.

21For, if thou do not let my people go, behold, I will send dog-flies upon thee, and upon thy bondmen, and upon thy people, and into thy houses; and the houses of the Egyptians shall be full of dog-flies, and also the ground on which they are.

22And I will distinguish in that day the land of Goshen, in which my people dwell, that no dog-flies shall be there; that thou mayest know that I Jehovah am in the midst of the land.

23And I will put a separation between my people and thy people; to-morrow shall this sign be.

24And Jehovah did so; and there came dog-flies in a multitude into the house of Pharaoh, and [into] the houses of his bondmen; and throughout the land of Egypt, the land was corrupted by the dog-flies.

25And Pharaoh called Moses and Aaron, and said, Go, sacrifice to your 1God in the land.

26And Moses said, It is not proper to do so; for we should sacrifice the abomination of the Egyptians to Jehovah our 2God: lo, if we sacrificed the abomination of the Egyptians before their eyes, would they not stone us?

27We will go three days' journey into the wilderness, and sacrifice to Jehovah our 3God, as he shall command us.