Exodus Chapter 7 Verses 19-21

:19 “And the LORD spake unto Moses, Say unto Aaron, Take thy rod, and stretch out thine hand upon the waters of Egypt, upon their streams, upon their rivers, and upon their ponds, and upon all their pools of water, that they may become blood; and that there may be blood throughout all the land of Egypt, both in vessels of wood, and in vessels of stone. 20 And Moses and Aaron did so, as the LORD commanded; and he lifted up the rod, and smote the waters that were in the river, in the sight of Pharaoh, and in the sight of his servants; and all the waters that were in the river were turned to blood. 21 And the fish that was in the river died; and the river stank, and the Egyptians could not drink of the water of the river; and there was blood throughout all the land of Egypt.”   

In this we see once again the order that God had prescribed for Moses and Aaron.  God would speak to Moses, who in turn would speak to Aaron, who in turn would speak to Pharaoh. 

Moreover, we see that God carried out the judgment just as he promised.  God’s judgments are sure just like his promises are sure.  When God promises judgment we can rest assured that God will bring forth that judgment just as he promised.   

To the Egyptians and to Pharaoh this judgment was a great blow to their economy as a big part of their economy and livelihood rested upon the catching and eating of fish.  Moreover the rivers and streams were their primary source of water and now because of God’s judgment their economy was hurt and they would have to frantically search for another source of water for their livelihood.   

All this was brought about because of Pharaoh’s hard heart and his refusal to let the children of Israel go out of Egypt. 

Verses 22-25 

:22 “And the magicians of Egypt did so with their enchantments: and Pharaoh's heart was hardened, neither did he hearken unto them; as the LORD had said. 23 And Pharaoh turned and went into his house, neither did he set his heart to this also. 24 And all the Egyptians digged round about the river for water to drink; for they could not drink of the water of the river. 25 And seven days were fulfilled, after that the LORD had smitten the river.”

A magician uses magic and enchantments to deceive and fool people into believing something to be true that is not true.  This tells us that Pharaoh was a believer in magic and no doubt he viewed what Moses and Aaron were doing as being great magic tricks.  Pharaoh is still looking at what is happening as a test of will and wit between him and all his power and strength and what he believed Moses and Aaron were doing with their (as he believed) magic tricks. 

This goes to show us that timely demonstrations of God’s power and judgments will not persuade unregenerate men into believing in God and believing God.   

In the meantime, the Egyptians became quite busy trying to find water to drink as they digged round about the river.  Pharaoh’s hard heart was putting a burden and load upon his own people.   

“And seven days were fulfilled, after that the LORD had smitten the river.”  Seven is the number in the scriptures that is associated with completion.  In this we see the LORD allowing the complete effects of his judgment to rest upon the Egyptians until the next judgment was sent.