Exodus 8:28-30

ASV(i) 28 And Pharaoh said, I will let you go, that ye may sacrifice to Jehovah your God in the wilderness; only ye shall not go very far away: entreat for me. 29 And Moses said, Behold, I go out from thee, and I will entreat Jehovah that the swarms of flies may depart from Pharaoh, from his servants, and from his people, to-morrow: only let not Pharaoh deal deceitfully any more in not letting the people go to sacrifice to Jehovah. 30 And Moses went out from Pharaoh, and entreated Jehovah.