Exodus 8:30 WBT

²⁸  And Pharaoh said, I will let you go, that ye may sacrifice to the LORD 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 the LORD that the swarms [of flies] may depart from Pharaoh, from his servants, and from his people, to-morrow: but let not Pharaoh deal deceitfully any more, in not letting the people go to sacrifice to the LORD.

³⁰  And Moses went out from Pharaoh, and entreated the LORD:

³¹  And the LORD did according to the word of Moses; and he removed the swarms [of flies] from Pharaoh, from his servants, and from his people; there remained not one.

³²  And Pharaoh hardened his heart at this time also, neither would he let the people go.