Then the LORD said to Moses, “Pharaoh’s heart is stubborn, and he still refuses to let the people go.
References for Exodus 7:14
So go to Pharaoh in the morning as he goes down to the river. Stand on the bank of the Nile and meet him there. Be sure to take along the staff that turned into a snake.
Then announce to him, ‘The LORD, the God of the Hebrews, has sent me to tell you, “Let my people go, so they can worship me in the wilderness.” Until now, you have refused to listen to him.
So this is what the LORD says: “I will show you that I am the LORD .” Look! I will strike the water of the Nile with this staff in my hand, and the river will turn to blood.
The fish in it will die, and the river will stink. The Egyptians will not be able to drink any water from the Nile.’”
Then the LORD said to Moses: “Tell Aaron, ‘Take your staff and raise your hand over the waters of Egypt—all its rivers, canals, ponds, and all the reservoirs. Turn all the water to blood. Everywhere in Egypt the water will turn to blood, even the water stored in wooden bowls and stone pots.’”
So Moses and Aaron did just as the LORD commanded them. As Pharaoh and all of his officials watched, Aaron raised his staff and struck the water of the Nile. Suddenly, the whole river turned to blood!
The fish in the river died, and the water became so foul that the Egyptians couldn’t drink it. There was blood everywhere throughout the land of Egypt.
But again the magicians of Egypt used their magic, and they, too, turned water into blood. So Pharaoh’s heart remained hard. He refused to listen to Moses and Aaron, just as the LORD had predicted.
Pharaoh returned to his palace and put the whole thing out of his mind.
Then all the Egyptians dug along the riverbank to find drinking water, for they couldn’t drink the water from the Nile.