Exodus 8:28-29

28Pharaoh said, “1I will let you go, that you may sacrifice to the Lord your God in the wilderness; only you shall not go very far away. 2Make supplication for me.” 29Then Moses said, “Behold, I am going out from you, and I shall make supplication to the Lord that the swarms of flies may depart from Pharaoh, from his servants, and from his people tomorrow; only do not let Pharaoh 3deal deceitfully again in not letting the people go to sacrifice to the Lord.”