On the last day of his life, Moshe began a song for the Jewish people by invoking the heavens as a witness. In the days leading up to Rosh Hashana and then Yom Kippur, prayer can be enhanced by awareness of the descriptions of G-d in this song.
Moshe sang “ascribe greatness to our G-d”, “The Rock, perfect is His work,for all His paths are justice; a G-d of faith without iniquity, righteous and fair is He”. R’ Munk wrote that no term better better describes the eternal constancy of G-d than the metaphor Rock. It was a word of great significance particularly for those who witnessed the Revelation at Sinai. R’ Hirsch wrote that justice may appear to us in different forms. Some aspects may remain inaccessible to our understanding, yet we accept this.
Then “corruption is not His”, which Rashi interpreted as meaning that the blame for sin and corruption should lie with mankind and not with G-d. Moshe asked “Is He not your Father, your Master?”” Has He not created you and firmed you?”
At the end of the song Moshe reminded the people to perform all the words of the Torah for “it is your life and through it you can prolong your days on the land to which you cross the Jordan to possess it”.
In Sifre it was written that “this song is great for it applies to the present, the past and to the future”.