The Rambam views the Shira of Haazinu as a prophecy of what would happen to Bnai Yisrael from the beginning of its history to our days. In this week’s Parsha it says ויבא משה וידבר את כל דברי השיה הזאת באזני העם הוא והושע בן נון (לב:מד), Moshe came and told all of the words of the Shira to Bnai Yisrael and Hoshea Bin Nun. The Rambam comments that the reason it says כל דברי, all the words is to show that this includes everything that would happen to us in the future. Although the Shira is very short, it contains many ideas. Moshe told the Shira orally so he could explain everything that will happen to them in great detail. The Rambam says that if the Shira was a document written by astrologers stating everything that will happen to us, it would be accepted by everyone because of its accuracy. So far, everything that the Shira said would happen has happened exactly as it said. This shows us how much more we should believe in Moshe, as he was the most faithful prophet to Hashem. As we say every morning in Davening, לא קם בישראל כמשה עוד, “There has been no one in Bnai Yisrael like Moshe, and there never will be.” The Shira has been true to its word. At first, it states that Hashem showed us his kindness. He did this when he chose us as his nation. The Shira then goes on to tell how Hashem did favor for us in the Midbar and how we inherited Eretz Yisrael with great wealth. Then, because of all this wealth and good, Bnai Yisrael rebelled and did Avoda Zara. Then as we all know, Hashem sent us famine and sword. This was the destruction of the Bait Hamikdash. History continued along the course described by the Shira. From the Rambam, we can see that the Shira is a prophecy, not a form of rebuke from Moshe to Bnai Yisrael, as other commentators explain.