Exodus 8:28-29

28Pharaoh said, “I will release you so that you may sacrifice to the Lord your God in the desert. Only you must not go very far. Do pray for me.”

29Moses said, “I am going to go out from you and pray to the Lord, and the swarms of flies will go away from Pharaoh, from his servants, and from his people tomorrow. Only do not let Pharaoh deal falsely again by not releasing the people to sacrifice to the Lord.”