Exodus 8:30 DBY

²⁸  And Pharaoh said, I will let you go, that you may sacrifice to Jehovah your God in the wilderness; only, go not very far away: intreat for me!

²⁹  And Moses said, Behold, I go out from thee, and will intreat Jehovah; and the dog-flies will depart from Pharaoh, from his bondmen, 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 intreated Jehovah.

³¹  And Jehovah did according to the word of Moses; and he removed the dog-flies from Pharaoh, from his bondmen, and from his people; there remained not one.

³²  And Pharaoh hardened his heart this time also, and would not let the people go.