I never use the term "Levitical Law".
I think that is your term.
In this passage, it is God, you know, the Almighty, speaking to Isaac.
God tells Isaac why He chose to bless Abraham, and eventually Abraham's Seed.
It is God that says, "Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws"
This is not man's opinion or commentary by man.
This is God speaking.
Why do you have an issue with that?