What was the purpose of the third set of forty days that Moshe spent on Har Sinai?
Rashi: It was to receive the second set of Luchos; and the Torah mentions it here to teach us how long he remained there. 1
Da'as Zekenim, Hadar Zekenim, Rosh: It was to receive the second Luchos and pray for a total pardon for Yisrael.
What are the implications of the words "ka'Yamim ha'Rishonim"?
Rashi: To teach us that these forty days were days of goodwill, just as the first ones were. 1 However, Hashem was angry during the middle forty days.
Ramban (citing the Seider Olam): To teach us that, during these forty days, Moshe Davened to Hashem with the thirteen Midos ('Hashem Hashem
Sifsei Chachamim: The first days, before Chet ha'Egel, were with total goodwill; the last days were not, seeing as Hashem said "Salachti ki'Devarecha" only at the end, on Yom Kipur. And they are only compared to the first days regarding Moshe receiving the Luchos. It is not necessary to say this however, acording to the opinion that Ba'alei Teshuvah are on a higher level than those who have not sinned. E.C,
Ramban: And just as He did the first time, Hashem answered Moshe positively, as the next Pasuk explains.
What are the implications of "Lo Avah Hashem Hashchisecha"?
Ramban #1: Hashem did not want you to lose coming to and inheriting Eretz Yisrael. 1
Ramban #2 (According to Kabalah): It implies that you should not be banished from Hashem's great Name - that it should not accompany you. 2