What are "ve'Zos ha'Torah ... " in this Pasuk and "Eileh ha'Eidos ... " in the following Pasuk referring to?
Rashi: They are referring to the Mitzvos that Moshe is about to repeat starting from the beginning of Perek 5. 1
Seforno: "ve'Zos ha'Torah ... " is referring to the part of Torah that is based on thought, that Moshe taught them until now, whereas "Eileh ha'Eidos ... " in the following Pasuk is referring to the testimonies that came as a result of the miracles that they witnessed. 2
Rashi: And that is also what the next Pasuk is referring to when it writes "Eileh ha'Eidos ... ," since it is the same Mitzvos that Hashem taught Moshe at Har Sinai that Moshe is now going to repeat at Arvos Mo'av.
It is not however clear why the Seforno ignores the Chukim and Mishpatim that the following Pasuk also mentions.