What are the Chukim and Mishpatim that Hashem commanded Moshe at Har Sinai to teach Yisrael?
Rashi: It refers to the Torah she'be'al Peh - to explain the Chukim and Mishpatim that Hashem had already taught them.
Ramban: It refers to the other Mitzvos, besides the Aseres ha'Dibros which they heard from Hashem directly.
Rashbam: Hashem commanded him to teach them the Aseres ha'Dibros. 1