Exodus 8:22

And Moses said, It cannot be so, for we shall sacrifice to the Lord our God the abominations of the Egyptians; for if we sacrifice the abominations of the Egyptians before them, we shall be stoned.

and I will distinguish marvelously in that day the land of Gesem, on which my people dwell, in which the dog-fly shall not be: that you may know that I am the Lord the God of all the earth.

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 thou mayest know that I am the Lord in the midst of the earth.