One of the obvious questions that emerges in this Parsha is why is Pharaoh asked to let the Jews go for 3 days instead of being set free altogether.
G-d declares that he has come to keep his word, he sends multiple catastrophies on Egypt and the request is shockingly modest. Merely to have the Jewish people go to serve him for three days. Then the implication is, they will go back.
The flip side of the question has to do with why Pharaoh continues to reject and fight against this modest request. It might be understandable that he would refuse to set the Jews free entirely, but to let them go for three days seems like a small thing especially compared to the devastation that Egypt endures.
Part of the answer to this question can be found in the differences of the English vs the Religious Hebrew names for the second book of the Torah. Exodus vs Shemos, 'Names.' Exodus is what most people think of when they think of the Jews leaving the slavery of Egypt. Yet this is not the name of Shemos and not even of the Parshas, the closest of which to that name is BeShalach, When Pharaoh Sent. Freedom is not what is really at issue here if we examine the religious Hebrew names given.
Shemos is a refferences to the lineage of the ancestry of the Jews. This is reiterated repeatedly throughout their slavery from the very beginning over and over again listing the descendants to the present day. The same ancestors who made a covenant with G-d. The next two Parshas are named after G-d's commands and appearances to Moshe. And this is the difference in priorities. While the popular view is that the story of the exodus from Egypt is about freedom, it is not at all. Indeed G-d spells it out specifically that the Jews have gone from being slaves to men, to coming to serve G-d.
Thus when Moshe comes to Pharaoh he does not come to ask for freedom for the Jews. He is asking that they be free to serve their true master, the creator of the world, G-d. This is a very different narrative from the popular one. Moshe is not demanding personal freedom, he is demanding the right of a people to serve G-d over men and proclaiming the autonomy of the worship of G-d over tyranny.
This is what is at stake here and if Pharaoh permits it, he is recognizing that G-d is the higher authority over men than him not only for three days but for all eternity.
Why three days then?
There are three times a year that G-d tells the Jews to appear before him. Pesach, Shavuot and Succot. Pesach commemorates the exodus from Egypt. Shavuot helps commemorate the giving of the Torah after the exodus. Succos commemorates the booths we lived in, in the desert, after the exodus from Egypt.
Each of those holidays is connected to the exodus from Egypt. Together these holidays are the three times the entire nation of Israel ascended to the Beit Hamikdash to worship G-d and comprised the centralization of the year around the worship of G-d. When Moshe asked for three days, he meant these three sets of days that would center a Jew's life around the worship of G-d all stemming from leaving Egypt. Those three days would change the Jews from slaves of Pharaoh to servants of G-d.