The tenth plague, the death of the firstborn, brought about the Passover. It called for extensive preparation each element signifying some aspect of their redemption (bitter herbs for the bitterness of slavery, for example). Read Exodus 12. Israel was to obey God's instructions and “keep this service” (observe this rite) as a lasting ordinance. This word “service” is the same word used in chapter 1 for slavery.
Explain how this new “service” to God would differ from service to Pharaoh.
To me, service to Pharaoh is like the work that I perform for my self welfare. It gives immediate satisfaction. May or may not be good on the long run. This needs to be in balance with the service to God. Service to God is stored in eternity where thieves cannot steal and moth cannot eat.
Another point that comes to mind is that when we serve the Pharaoh, aren't we serving the gods that the Pharaoh considers as gods? Instead we can worship the true God. The plagues themselves clearly indicate that God proved to the Egyptians that the gods that worship are helpless. The frogs, locusts I believe were part of their list of gods.
