-It says “I will harden the heart of Pharaoh and he will not let them go.”
-Indeed Pharaoh did not let Yisroel go until his country was destroyed.
-One of the basic parts of our religion is that G-D gives free will to every human. It is very wrong to say that G-D forced Pharaoh to enslave the Jews and at the same time punish him for it.
-There are two aspects to not giving in. The first is the will to not give in, and the second is energy needed to not give in. Meaning, a person might not want to give in but there is so much pressure, that he doesn’t have the stamina to hold back. For example if a person is tortured he will give in, not because he wants to, but because he does not have any energy left.
-Pharaoh’s will was never taken out of his control, he was simply given more energy to bring into action what he really wanted.

( Rabbi Yonasan, Tiferet Yonason - Bo )