On this, the last day of his life, Moshe goes from tent to tent throughout the camp, bidding farewell to his beloved people, encouraging them to keep the faith. Moshe tells them that whether he is among them or not, G-d is with them, and will vanquish their enemies. Then he summons Yehoshua, and in front of all the people, exhorts him to be strong and courageous as the leader of the Jewish People. In this manner, he strengthens Yehoshua's status as the new leader. Moshe teaches them the mitzvah of Hakhel: That every seven years on the first day of the intermediate days of Succos, the entire nation, including small children, is to gather together at the Temple to hear the King read from the Book of Devarim. The sections that he reads deal with faithfulness to G-d, the covenant, and reward and punishment. G-d tells Moshe that his end is near, and he should therefore summon Yehoshua to stand with him in the Mishkan, where G-d will teach Yehoshua. G-d then tells Moshe and Yehoshua that after entering the Land, the people will be unfaithful to Him, and begin to worship other gods. G-d will then completely hide his face, so that it will seem that the Jewish People are at the mercy of fate, and that they will be hunted by all. G-d instructs Moshe and Yehoshua to write down a song -Ha'azinu - which will serve as a witness against the Jewish People when they sin. Moshe records the song in writing and teaches it to Bnei Yisrael. Moshe completes his transcription of the Torah, and instructs theLevi'im to place it to the side of the Aron (Holy Ark), so that no one will ever write a new Torah scroll that is different from the original - for there will always be a reference copy.
Prose and Poetry
“And Moshe wrote this poem…” (31:22)
Prose and poetry are worlds apart.
Prose is more or less like someone speaking from a page.
No one speaks like a poem.
Prose is speech committed to writing.
Poetry is a written concentration of words divulged by speech.
Moshe transmitted the Torah to the Jewish People first by speech – as a prose experience. It was then committed to writing. This was akin to a lecture – the Oral Torah – that was then written down as the notes of that lecture. That is a comparison to the written Torah.
This is the part of the Torah that we might call prose.
However, there is another part to the Torah: its poetry.
“And Moshe wrote this poem…”
This poem, this shira, that visualizes G-d, was given first as a written quintessence and only then came the Oral tradition to correctly explain it.
A poem comes from beyond the literal, beyond the tangible. It uses words to escape language.
The words of the poem soar above language, and the Oral commentary is the ladder given to ascend to its lofty sentiments.
Source: based on Rabbi Samson Raphael Hirsch