Moses and Aaron did all these wonders before Pharaoh, but the LORD hardened Pharaoh's heart so that he would not let the Israelites go out of his land.

John 12:40
"He has blinded their eyes and hardened their hearts, so that they cannot see with their eyes, and understand with their hearts, and turn, and I would heal them."

Romans 9:18
Therefore God has mercy on whom He wants to have mercy, and He hardens whom He wants to harden.

Exodus 4:21
The LORD instructed Moses, "When you go back to Egypt, see that you perform before Pharaoh all the wonders that I have put within your power. But I will harden his heart so that he will not let the people go.

Exodus 7:3
But I will harden Pharaoh's heart, and though I will multiply My signs and wonders in the land of Egypt,

Exodus 9:12
But the LORD hardened Pharaoh's heart, and he would not listen to them, just as the LORD had said to Moses.

Exodus 10:20
But the LORD hardened Pharaoh's heart, and he would not let the Israelites go.

Exodus 10:27
But the LORD hardened Pharaoh's heart, and he was unwilling to let them go.

Exodus 12:1
Now the LORD said to Moses and Aaron in the land of Egypt,

Joshua 11:20
For it was of the LORD to harden their hearts to engage Israel in battle, so that they would be set apart for destruction and would receive no mercy, being annihilated as the LORD had commanded Moses.

Isaiah 63:17
Why, O LORD, do You make us stray from Your ways and harden our hearts from fearing You? Return, for the sake of Your servants, the tribes of Your heritage.

And Moses and Aaron did all these wonders before Pharaoh: and the LORD hardened Pharaoh's heart, so that he would not let the children of Israel go out of his land.