Indeed, in my humble opinion, it seems we can explain the reason for seeking permission in another way. In the morning blessings of the Shema, we say: "You redeemed us from Egypt and liberated us from the house of slavery." We should ponder this, as it seems that "Egypt" and "the house of slavery" are one and the same, and "redemption" and "liberation" are also the same. What is the meaning of this duplication?

It is conveyed in the name of Rabbi Chaim Halevi Soloveitchik (see Haggadah of Pesach, Beit Levi, page 189) that there were two aspects to the exile in Egypt. The first was the actual enslavement, where they worked for Pharaoh with hard labor. The second was the status of slavery, where their bodies were owned by Pharaoh as slaves. Regarding these two aspects, we repeat and say "You redeemed us from Egypt" and "liberated us from the house of slavery." That is to say, "You redeemed us from Egypt" – from the hard labor we worked in the land of Egypt, and for this, the term "redemption" is appropriate, as it means freeing us from the hard labor. "Liberated us from the house of slavery" – from the ownership of our bodies, for we were sold as slaves, and for this, the term "liberation" is appropriate, as it means the nullification of the ownership of slavery.

There is evidence of this in the Gemara (Rosh Hashanah 11a), which states that already on Rosh Hashanah, that is, six months before the redemption of our ancestors from Egypt, the labor ceased. It seems difficult, for if so, what was the manifestation of the redemption in Nissan, since they had already been free from labor for half a year? According to Rabbi Chaim's words, it is well understood. Even though the labor ceased, the ownership of slavery did not end until their redemption in Nissan.

From now on, we can say that this is why Moses needed to compel Pharaoh to declare, "You are in your own authority, you are free people" – to nullify the ownership of slavery. Even though they were free to leave, as Pharaoh no longer detained them, the ownership of slavery still needed to be nullified.

We are privileged to have an additional explanation for the verse "When Pharaoh let the people go" – which refers to the nullification of the ownership of slavery. Since this matter indeed depended on him, and the Israelites needed him for this, the scripture attributes it to him and says, "When Pharaoh let the people go," as if it were saying, "When Pharaoh liberated them."