20 And the LORD said unto Moses, Rise up early in the morning and stand before Pharaoh; behold, he goes forth to the water and say unto him, The LORD hath said thus, Let my people go that they may serve me. 21 For if thou wilt not let my people go, behold, I will send swarms of flies upon thee and upon thy slaves and upon thy people and into thy houses; and the houses of the Egyptians shall be full of all kinds of flies and also the ground upon which they are. 22 And I will separate in that day the land of Goshen, in which my people dwell, that no kind of flies shall be there to the end that thou may know that I am the LORD in the midst of the earth. 23 And I will put redemption between my people and thy people. Tomorrow shall this sign be. 24 And the LORD did so: that there came a grievous swarm of flies into the house of Pharaoh and into his slaves’ houses and into all the land of Egypt; and the land was corrupted by reason of the swarm of flies.
25 Then Pharaoh called for Moses and for Aaron and said, Go ye, sacrifice to your God in the land of Egypt. 26 And Moses replied, It is not convenient to do so; for we shall sacrifice the abomination of the Egyptians to the LORD our God. Behold, if we sacrifice the abomination of the Egyptians before their eyes, will they not stone us? 27 We will go three days’ journey into the wilderness and sacrifice to the LORD our God as he has said unto us. 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; pray for me. 29 And Moses answered, Behold, as I go out from thy presence, I will intreat the LORD that the swarms of flies may depart from Pharaoh, from his slaves, and from his people tomorrow; if Pharaoh will not deal deceitfully any more in not letting the people go to sacrifice to the LORD. 30 Then Moses went out from Pharaoh, and prayed unto the LORD. 31 And the LORD did according to the word of Moses, and he removed the swarms of flies from Pharaoh, from his slaves, and from his people; there remained not one. 32 And Pharaoh even hardened his heart this time and did not let the people go.