Thus, although Moses and Aaron performed all these wonders in Pharaoh’s presence, the Lord hardened Pharaoh’s heart, and he would not let the Israelites go from his land.
The Lord said to Moses: On your return to Egypt, see that you perform before Pharaoh all the wonders I have put in your power. But I will harden his heart and he will not let the people go.
Pharaoh will not listen to you. Therefore I will lay my hand on Egypt and with mighty acts of judgment I will bring my armies, my people the Israelites, out of the land of Egypt.
But although Pharaoh found upon inquiry that not even so much as one of the livestock of the Israelites had died, he remained obstinate and would not let the people go. Sixth Plague: The Boils.
“He blinded their eyes and hardened their heart, so that they might not see with their eyes and understand with their heart and be converted, and I would heal them.”
For it was the Lord’s doing to make their hearts obstinate to meet Israel in battle, that they might be put under the ban without mercy, and be destroyed as the Lord had commanded Moses.