Exodus 7:14–25 (CSB)

THE FIRST PLAGUE: WATER TURNED TO BLOOD

14 Then the LORD said to Moses, “Pharaoh’s heart is hard: He refuses to let the people go. 15 Go to Pharaoh in the morning. When you see him walking out to the water, stand ready to meet him by the bank of the Nile. Take in your hand the staff that turned into a snake. 16 Tell him: The LORD, the God of the Hebrews, has sent me to tell you: Let my people go, so that they may worship me in the wilderness. But so far you have not listened. 17 This is what the LORD says: Here is how you will know that I am the LORD. Watch. I am about to strike the water in the Nile with the staff in my hand, and it will turn to blood. 18 The fish in the Nile will die, the river will stink, and the Egyptians will be unable to drink water from it.”
19 So the LORD said to Moses, “Tell Aaron: Take your staff and stretch out your hand over the waters of Egypt—over their rivers, canals, ponds, and all their water reservoirs—and they will become blood. There will be blood throughout the land of Egypt, even in wooden and stone containers.”
20 Moses and Aaron did just as the LORD had commanded; in the sight of Pharaoh and his officials, he raised the staff and struck the water in the Nile, and all the water in the Nile was turned to blood. 21 The fish in the Nile died, and the river smelled so bad the Egyptians could not drink water from it. There was blood throughout the land of Egypt.
22 But the magicians of Egypt did the same thing by their occult practices. So Pharaoh’s heart was hard, and he would not listen to them, as the LORD had said. 23 Pharaoh turned around, went into his palace, and didn’t take even this to heart. 24 All the Egyptians dug around the Nile for water to drink because they could not drink the water from the river. 25 Seven days passed after the LORD struck the Nile.