1)
Why does the Torah need to add "Luchos ha'Beris"?
1.
Oznayim la'Torah: To explain to Yisrael why Moshe needed to be on Har Sinai for forty days, even though the Luchos were already written earlier - because Hashem only entered into a covenant with Yisrael on account of Torah she'be'Al Peh - which Moshe only completed at the end of forty days. 1
1
See Oznayim la'Torah, who elaborates.
