What does Exodus 9:14 mean?

God's prediction here clearly indicates that the upcoming seventh plague (Exodus 3:20) would not be the last. The Hebrew text literally says the plagues will be sent "on your heart." This figure of speech indicates a personal emphasis on Pharaoh. The Lord clarifies the reason for these plagues, which is to demonstrate His glory and power. Egypt was the most powerful nation on earth at that time. The series of plagues would prove that neither Egypt nor their false gods were anything compared to the One True God.

Part of this judgment is using Pharoah as an example for history. After repeatedly defying the Lord (Exodus 5:2; 7:13–14, 22; 8:15, 19, 32; 9:7), Pharaoh has one last chance. He will fail once again (Exodus 9:34–35) and lose any opportunity to avoid disaster (Exodus 4:21–23). From now on, God will complete His message by "hardening" Pharaoh to incite further calamities (Exodus 10:1, 20, 27; 11:10; 14:8). To some, this seems unfair. But Pharaoh has been given numerous chances (Exodus 5:1; 7:16; 8:1, 21; 9:1). God could have wiped out the entire nation if He so chose (Exodus 9:15). Pharaoh's own sin has brought him past the point of no return (Proverbs 29:1; Exodus 9:16–17).

In Isaiah 46:9 the Lord notes, "I am God, and there is no other; I am God, and there is none like me." In Isaiah's context, God contrasts His greatness against the idols of Babylon. He is superior to imaginary gods made by people. God exhibits supreme power over all creation, including times of judgment against those who oppose His will and His people.