What does Exodus 9:12 mean?
This final verse concerning the sixth plague (Exodus 9:8–11) summarizes Pharaoh's response. Here, for the first time, we see the Lord actively interfering with Pharaoh's mindset. God promised to "harden" the Egyptian king (Exodus 4:21; 7:3–4) to use him as an example. To this point, however, Pharaoh has chosen stubbornness of his own free will (Exodus 5:2; 7:13–14, 22; 8:15, 19, 32; 9:7). Now, after ignoring another obvious miracle (Exodus 9:5–6), he is about to become an object of God's wrath.This will lead to the next plague: a terrifying storm of hail and lightning (Exodus 9:24–25). Afterward, Pharaoh will once again make his own choice to ignore the Lord (Exodus 9:34–35). From then on, he will be entirely given over (Proverbs 29:1) to his fate as a living warning (Exodus 10:1, 20, 27; 11:10; 14:8). The king defied God over and over. Eventually, his opportunities for mercy were lost. Everything which happens to Pharaoh after the next plague is entirely the result of his own obstinate sin.