Then the LORD said to Moses, "Pharaoh is stubborn. He still refuses to let the people go.
References for Exodus 7:14
Go to Pharaoh in the morning. As he is going out to the water, make sure you stand at the bank of the Nile River so you will run into him. Bring along the shepherd's rod that turned into a snake.
Say to him, The LORD, the Hebrews' God, has sent me to you with this message: Let my people go so that they can worship me in the desert. Up to now you still haven't listened.
This is what the LORD says: By this you will know that I am the LORD. I'm now going to hit the water of the Nile River with this rod in my hand, and it will turn into blood.
The fish in the Nile are going to die, the Nile will stink, and the Egyptians won't be able to drink water from the Nile."
The LORD said to Moses, "Say to Aaron, ‘Take your shepherd's rod and stretch out your hand over Egypt's waters—over their rivers, their canals, their marshes, and all their bodies of water—so that they turn into blood. There will be blood all over the land of Egypt, even in wooden and stone containers.'"
Moses and Aaron did just as the LORD commanded. He raised the shepherd's rod and hit the water in the Nile in front of Pharaoh and his officials, and all the water in the Nile turned into blood.
The fish in the Nile died, and the Nile began to stink so that the Egyptians couldn't drink water from the Nile. There was blood all over the land of Egypt.
But the Egyptian religious experts did the same thing with their secret knowledge. As a result, Pharaoh remained stubborn, and he wouldn't listen to them, just as the LORD had said.
Pharaoh turned and went back to his palace. He wasn't impressed even by this.
Meanwhile, all the Egyptians had to dig for drinking water along the banks of the Nile River, because they couldn't drink the water of the Nile itself.
Seven days went by after the LORD had struck the Nile River.