The Lord spoke to Moses: "See, I have made you like God before Pharaoh, and Aaron your brother shall be your prophet. Speak all that I command, and Aaron shall declare it before Pharaoh: 'Let My people go.' But I will harden Pharaoh's heart. Though I perform signs and wonders, he will not listen. Then I will stretch out My hand with mighty judgments, and the Egyptians will know that I am the Lord when I bring Israel out from among them."
Moses was eighty years old, and Aaron eighty-three, when they stood before Pharaoh.
The Lord said, "When Pharaoh demands a sign, tell Aaron to cast down his staff, and it will become a serpent."
So before Pharaoh and his court, Aaron threw down the staff, and it writhed into a living serpent. Pharaoh's wise men and magicians did the same with their secret arts—each staff becoming a serpent. But Aaron's serpent swallowed theirs whole. Yet Pharaoh's heart grew hard, and he would not listen.
Then the Lord spoke again: "Pharaoh's heart is stubborn. Tomorrow morning, meet him by the Nile with the staff that became a serpent. Say to him: 'The Lord, the God of the Hebrews, has sent me to command you—let My people go, that they may worship Me in the wilderness. But you have refused. Now you shall know that I am the Lord. Behold, I will strike the waters of the Nile with this staff, and they will turn to blood. The fish will die, the river will stink, and the Egyptians will be unable to drink.'"
The Lord commanded Moses to tell Aaron: "Stretch out your staff over all the waters of Egypt—its rivers, its canals, its ponds, and its reservoirs—and they will turn to blood. Even the wooden buckets and stone jars will be filled with blood."
Moses and Aaron obeyed. Before Pharaoh's eyes, Aaron raised the staff and struck the Nile. At once its waters turned to blood. Fish floated lifeless, and the river reeked so foul that no one could drink from it. Blood spread throughout all Egypt.
But the magicians of Egypt mimicked this wonder with their secret arts, and Pharaoh's heart remained unyielding. He turned back into his palace, unmoved. Meanwhile, the Egyptians dug along the Nile's banks, desperate for water to drink.
Seven days passed after the Lord struck the Nile.