NOTE: The reader is reminded that the overall application of the truths we are currently seeing in this portion of the book of Exodus is simply that:
Pharaoh's objections reflect the same pressures believers encounter in the world as they seek to genuinely worship the true and living God. While studying through this portion of the book one would do well to continually ask the question: How have I personally experienced these same pressures from the world as I have sought to truly worship the LORD?
20 And the LORD said unto Moses, Rise up early in the morning, and stand before Pharaoh; lo, he cometh forth to the water; and say unto him, Thus saith the LORD, Let my people go, that they may serve me.
21 Else, if thou wilt not let my people go, behold, I will send swarms of flies upon thee, and upon thy servants, and upon thy people, and into thy houses: and the houses of the Egyptians shall be full of swarms of flies, and also the ground whereon they are.
22 And I will sever in that day the land of Goshen, in which my people dwell, that no swarms of flies shall be there; to the end thou mayest know that I am the LORD in the midst of the earth.
23 And I will put a division between my people and thy people: tomorrow shall this sign be.
24 And the LORD did so; and there came a grievous swarm of flies into the house of Pharaoh, and into his servants' houses, and into all the land of Egypt: the land was corrupted by reason of the swarm of flies.
Previously pharaoh had refused to let Israel go, even when confronted with plagues that his own magicians could not mimic. Now the LORD sends Moses and Aaron back to pharaoh to demand that he let Israel go, or face a great plague of flies in the land. Furthermore, the flies would not be found in the land of Goshen among the Hebrew people. The LORD made it clear that this new plague would begin the next day. This differentiation was intended to establish that the God of the Hebrews is the one true God.
25 And Pharaoh called for Moses and for Aaron, and said, Go ye, sacrifice to your God in the land.
26 And Moses said, It is not meet so to do; for we shall sacrifice the abomination of the Egyptians to the LORD our God: lo, shall we sacrifice the abomination of the Egyptians before their eyes, and will they not stone us?
27 We will go three days' journey into the wilderness, and sacrifice to the LORD our God, as he shall command 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: 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, tomorrow: 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.