Oh...you want to "apply" God's Word to Pharaoh, do you? Then apply these passages which I'll quote in chronological order and see if you're capable of connecting the dots:
Gen 15:12-16
12 As the sun was setting, Abram fell into a deep sleep, and a thick and dreadful darkness came over him. 13 Then the LORD said to him, "KNOW for certain that your descendants will be strangers in a country not their own, and they will be enslaved and mistreated four hundred years. 14 But I will punish the nation they serve as slaves, and afterward they will come out with great possessions. 15 You, however, will go to your fathers in peace and be buried at a good old age. 16 In the fourth generation your descendants will come back here, for the sin of the Amorites has not yet reached its full measure."
NIV
And then this:
Ex 3:18-20
18 "The elders of Israel will listen to you. Then you and the elders are to go to the king of Egypt and say to him, 'The LORD, the God of the Hebrews, has met with us. Let us take a three-day journey into the desert to offer sacrifices to the LORD our God.' 19 But I KNOW that the king of Egypt will not let you go unless a mighty hand COMPELS him. 20 So I will stretch out my hand and strike the Egyptians with all the wonders that I will perform among them. After that, he will let you go.
NIV
And finally:
Ex 4:21-23
21 The LORD said to Moses, "When you return to Egypt, see that you perform before Pharaoh all the wonders I have given you the power to do. But I will harden his heart so that he will not let the people go. 22 Then say to Pharaoh, 'This is what the LORD says: Israel is my firstborn son, 23 and I told you, "Let my son go, so he may worship me." But you refused to let him go; so I will kill your firstborn son.'"
NIV
How did God know for certain in the first passage above that Israel would be enslaved and oppressed by the Egyptians? You FWers will say, "Well, that's easy! God's foreknowledge! God gazed into his cosmic crystal ball and saw what will happen. Is that how all prophecy is fulfilled? Or is prophecy fulfilled by divine prerogative, i.e. divine decree?
Same kind of question for the second passage. How did God know that Pharaoh would not let God's covenant people go. More crystal gazing? Yet, the passage says that Pharaoh will let the people go AFTER God FORCES Pharaoh's hand. God was clearly playing a very active role in his rescue operation of the ancient Hebrews. It doesn't sound as though God was just passively watching human history unfold.
And more solid proof of this is in the last passage. How God KNEW that Pharaoh would not let His people go was not by mere crystal ball gazing, but rather by divine prerogative, i.e. His eternal decree! God's prophecies above came to past because God himself would proactively harden Pharaoh's heart, thereby also demonstrating the profound truth taught in Prov 21:1!