Exodus 8:21-23

New Revised Standard Version, Anglicised Catholic Edition

²¹ For if you will not let my people go, I will send swarms of flies on you, your officials, and your people, and into your houses; and the houses of the Egyptians shall be filled with swarms of flies; so also the land where they live. ²² But on that day I will set apart the land of Goshen, where my people live, so that no swarms of flies shall be there, that you may know that I the Lord am in this land. ²³ Thus I will make a distinction^[a] between my people and your people. This sign shall appear tomorrow.”’