Then the LORD said to Moses, "Pharaoh's heart is very stubborn. He refuses to let the people go.
References for Exodus 7:14
In the morning Pharaoh will go down to the water. Go and wait on the bank of the Nile River to meet him. Take in your hand the wooden staff that turned into a snake.
"Say to Pharaoh, 'The Lord, the God of the Hebrews, has sent me to you. He says, "Let my people go. Then they will be able to worship me in the desert. But up to now you have not listened."
" 'The LORD says, "Here is how you will know that I am the Lord. I will strike the water of the Nile River with the staff that is in my hand. The river will turn into blood.
The fish in the river will die. The river will stink. The Egyptians will not be able to drink its water." ' "
The LORD said to Moses, "Tell Aaron, 'Get your staff. Reach your hand out over the waters of Egypt. The streams, waterways, ponds and all of the lakes will turn into blood. There will be blood everywhere in Egypt. It will even be in the wooden buckets and stone jars.' "
Moses and Aaron did exactly as the LORD had commanded them. Aaron held out his staff in front of Pharaoh and his officials. He struck the water of the Nile River. And all of the water turned into blood.
The fish in the Nile died. The river smelled so bad the Egyptians couldn't drink its water. There was blood everywhere in Egypt.
But the Egyptian magicians did the same things by doing their magic tricks. So Pharaoh's heart became stubborn. He wouldn't listen to Moses and Aaron, just as the LORD had said.
Even that miracle didn't change Pharaoh's mind. In fact, he turned around and went into his palace.
All of the Egyptians dug holes near the Nile River to get drinking water. They couldn't drink water from the river.