A question might arise, why did God and the Hebrews not forgive the Pharaoh. Well Moses did tried his best to change Pharaoh’s heart. But he didn’t pay heed.

Christians like to say that "the pharaoh hardened his own heart", trying to put all the blame into the pharaoh's free will and exempting god. The thing is that before Moses even set foot in Egypt, god told him that the pharaoh would harden his own heart. If God ordains for a thing to happen, it must happen. So according to the text, that means the part where pharaoh hardens his own heart is just merely his heart being hardened in the passive sense by God. God planned it all, start to finish.