But the Lord hardened Pharaohs heart and he would not listen to Moses and Aaron, just as the Lord had said to Moses.
It was God who hardened Pharaoh's heart.
The phrase it was god who hardened Pharaoh's heart is simply a summation, and is no more literal than saying a philandering wife or husband hardened yours...not that I'm comparing God or his actions to a philandering spouse, mind you.
As such, if you are suggesting here that Pharaoh's demeano,r is actually God's demeanor by proxy, then I obviously disagree...
No, I'm not suggesting that God's demeanor was anything like Pharaoh's. I am suggesting, though, that it was part of God's plan that Pharaoh do what he did. To accomplish His plan, God left Pharaoh to his sinful nature SUCH THAT it was guaranteed that Pharaoh, in this case, would not listen to Moses and Aaron.