Then the Lord said to Moses, “Pharaoh's heart is hardened; he refuses to let the people go. Go to Pharaoh in the morning, as he is going out to the water. Stand on the bank of the Nile to meet him, and take in your hand the staff that turned into a serpent. And you shall say to him, ‘The Lord, the God of the Hebrews, sent me to you, saying, “Let my people go, that they may serve me in the wilderness. But so far, you have not obeyed.” Thus says the Lord, “By this you shall know that I am the Lord: behold, with the staff that is in my hand I will strike the water that is in the Nile, and it shall turn into blood. The fish in the Nile shall die, and the Nile will stink, and the Egyptians will grow weary of drinking water from the Nile.”’” And the Lord said to Moses, “Say to Aaron, ‘Take your staff and stretch out your hand over the waters of Egypt, over their rivers, their canals, and their ponds, and all their pools of water, so that they may become blood, and there shall be blood throughout all the land of Egypt, even in vessels of wood and in vessels of stone.’”
Moses and Aaron did as the Lord commanded. In the sight of Pharaoh and in the sight of his servants he lifted up the staff and struck the water in the Nile, and all the water in the Nile turned into blood. And the fish in the Nile died, and the Nile stank, so that the Egyptians could not drink water from the Nile. There was blood throughout all the land of Egypt. But the magicians of Egypt did the same by their secret arts. So Pharaoh's heart remained hardened, and he would not listen to them, as the Lord had said. Pharaoh turned and went into his house, and he did not take even this to heart. And all the Egyptians dug along the Nile for water to drink, for they could not drink the water of the Nile.
Seven full days passed after the Lord had struck the Nile.
Exodus 7:14-25
An examination of the plagues shows that there is both progression and development in them. For example, in the two recorded here, the serpents (10-12) and the blood (20-22), and in the next, the frogs (8:6, 7), the Egyptian magicians were able to imitate divine power, whereas in the later miracles they were unable to do so. There are several thoughts here. On the one hand, we are reminded that Satan can imitate God, but is unable to do anything original or creative, not being an 'original thinker'. We should recall in this connection the terrible imitative trinity of evil in the book of Revelation, the dragon, the beast and the false prophet, standing over against the Holy Trinity of Father, Son and Holy Ghost. It is not without significance, however, that the Egyptian magicians do not, in the exercise of their power, undo the miraculous work of God by turning the serpents back into rods, or the blood back into water. Only God can do that. The evil power is always negative and destructive. But there is something else. The fact that presently the Egyptian sorcerers were unable even to imitate the divine power is an indication not only that they were beaten, but also - far more significant - that God was now turning in real earnest to deal with them. It is as if, at the outset of the miracles, God had been patient and forbearing, smiling almost (cf Psalm 2:4), at their attempts to rival His power - 'Let Me see how many miracles you can do' - but then the smile of forbearance disappears, and a grimness comes upon His holy face, and He begins to deal in earnest with them, putting pressure upon them, and taking the offensive against them. It is amazing just how much rope God gives to men in their arrogant rebellion against Him, but there comes a time when He finally says, 'That will be enough'. That time was soon to come for Pharaoh.