Parshat Haazinu is often read on Shabbat Shuva, but what does the Parsha have to do with Teshuva? The obvious place to look for the answer is in the content of the Parsha. This Parsha is a שירה, in which Moshe tells Bnai Yisrael that they will do Averot and they will get punished. If this is the case why is it called a שירה? The Lubavitcher Rebbe says that the answers to these questions can be found in a Midrash that discusses a conversation between Moshe and Hashem based on Pesukim from Tehillim. Moshe tells Hashem לא אמות כי אחיה ואספר מעשה יה..., “I should not die so I can tell the world the wonders of Hashem.” Hashem shows Moshe his portion in עולם הבא, and Moshe says פתחו לי שערי צדק..., “Open up the gates of righteousness, I’ll die so I can go into עולם הבא.” The Midrash does not seem to make sense. Moshe Rabbeinu, who dedicated his whole life to Bnai Yisrael, when he sees his portion in עולם הבא he says “forget Bnai Yisrael”? The Rebbe answers that Hashem showed Moshe that even though Bnai Yisrael sinned they will do Teshuva and they will be forgiven. So Moshe said if that is the case then he can die. From this we can understand why Haazinu is call a שירה and why it is read on Shabbat Shuva. The reason is that Haazinu describes how in the future we will sin, but we have to understand that we still can do Teshuva and be redeemed and bring משיח.