Why did God send Moses to Pharaoh saying, "let my people go! Repent" if God had already told Moses that Pharaoh would not let my people go, as it is written, "I realize that you and your subjects still do not fear God." (Exodus 9:30)? The reason God sent Moses to Pharaoh is expressed in the passage, "The only reason I let you survive was to show you My strength, so that My name will be discussed all over the world." (Exodus 9:16). God wanted to let mankind know that when He prevents a sinner from repenting, he will indeed die for the wickedness that he had committed willfully.
Likewise with Sichon, because of previous sins he was prevented from repenting, as it is written, "God had hardened his spirit and made his heart firm . . ." (Deuteronomy 2:30).
Similarly, the Canaanites, were prevented from repenting because of their loathsome way of life, thus they waged war against the Israelites, as it is written, "For it was God's doing to stiffen their hearts to do battle with Israel in order that they be destroyed." (Joshua 11:20).
In the same way, the Jews in the days of Elijah committed many wrongs. Those who committed many sins were prevented from repenting, as it is written, "You have turned their hearts backward." (Kings I, 18:37).
To summarize, God did not decree that Pharaoh harm the Jews, nor that Sichon sin in his land, nor that the Canaanites perform despicable acts, nor that the Jews worship idols. It was their own idea to commit sins and as punishment they were precluded from repenting3.
[6:4] The righteous people and the prophets had this in mind when they prayed to God to guide them on the path of truth so that they may repent and not rest in falsehoods. King David said, "Teach me Your way, O God, that I may walk in Your truth." (Psalms 86:11), meaning, do not let my sins prevent me from reaching the path of truth which will lead me to appreciate Your ways and the unity (perfection) of Your name. The same idea is expressed in, "Sustain me with a generous spirit." (Psalms 51:14), meaning, let my spirit be willing to do Your will, and do not let my sins close the gates of repentance for me. Rather, let me choose to repent, following the path of truth. All similar verses should be interpreted along these lines.
[6:5] What did King David mean when he said, "therefore He directs sinners on the way. He guides the lowly in the right path, and teaches the lowly His way." (Psalms 25:9)? (By guiding people on the right path, it would seem that God makes it impossible for them to choose evil). King David meant that God sends prophets letting the people know the path of God and inspiring them to repent. King David implies that God gave people the capacity to learn and understand.
A universal characteristic of all mankind is, that the more one follows the paths of wisdom and righteousness, the more good one desires and pursues. The Sages explain, "If one comes to cleanse himself, he is helped," (Shabbos 104a). Meaning, he receives help from heaven.
The verse, "And God said to Abraham, you shall surely know that your descendants will be strangers in a foreign land where they will be enslaved and oppressed for four hundred years," (Genesis 15:1), implies that God decreed on the Egyptians to treat the Jews harshly. It also says, "This nation shall rise up and stray after the alien gods of the land." (Deuteronomy 51:16). This seems to suggest that God decreed Jews would worship idols. If so, why did He punish them? Answer, God did not decree that a particular individual worship idols. God was speaking generally; there will be Jews who worship idols. Each person who worshiped idols had the option not to do so. It is as though God told Moses; Among the Jewish nation there will be righteous and wicked people. However, a wicked man can not say, "I am destined to be an evildoer, for God told Moses there will be evildoers among the Jewish people." Similarly it is written, "The poor will never cease to exist in the land." (Deuteronomy 15:11); (that does not mean a given individual will be poor. It means some people, not everyone, will be poor). The same can be said of the Egyptians. Any Egyptian who abused a Jew had the option to treat him kindly. God did not order any particular Egyptian to harm the Jews; He merely told Abraham that in time to come, his descendants would be enslaved in a foreign country. I already mentioned earlier that the human mind is incapable of fathoming how God knows the future.
3 The question is, how appropriate is the word "repenting" in this situation? Pharaoh was prevented from giving in to coercion and had no intention of repenting. When he did let them go, it was out of fear for his own life and not because he regretted his actions. Furthermore, how can he be punished for actions that he was forced to do? He can be punished for actions that he had a choice not to do, and further punished by not letting him repent those deeds so that he will be punished and not forgiven. The answer is, that Pharaoh had a choice by not reacting negatively to Moses' demand in the name of God to let the Jews go. Instead, after Moses made this demand, he increased the hardship on the Jews. For these sins, he was not allowed to repent.