At the end of Parashat Vayelech Moshe gives us the commandment:
וְעַתָּה כִּתְבוּ לָכֶם אֶת הַשִּׁירָה הַזֹּאת וְלַמְּדָהּ אֶת בְּנֵי יִשְׂרָאֵל שִׂימָהּ בְּפִיהֶם לְמַעַן תִּהְיֶה לִּי הַשִּׁירָה הַזֹּאת לְעֵד בִּבְנֵי יִשְׂרָאֵל.
Now write for you this song and teach it to the Children of Israel put it in their mouths so that this song will be a witness against the Children of Israel
On the surface this commandment seems to obligate us to write down the song of Parashat HaAzinu, next week’s Parsha, and to teach it to the Jewish People. But as it turns out, the command to write this song is actually the source for the positive commandment obligating every Jewish male adult to write a Sefer Torah or have one written on his behalf.
The Gemara, Nedarim 38. Expounds on the end of the pasuk to explain the reasoning, stating:
אי שירה לבדה קאמר מאי סהדותא איכא?
Since the Mitzva is referring to a Song which is intended to serve as testimony, if it is referring only to HaAzinu, what testimony is in that?
The Song of HaAzinu illustrates the general message that the trials and tribulations of Jewish history, along with the times of blessing and serenity, are dependent upon the Jewish people fulfilling their G-d given task. However, without the rest of the Torah there is no account of how we are meant to fulfill that task and therefore it is not a very effective testimony. As the only way to know the details of our obligation in this world is through Torah knowledge, it is clear that the Song written as a witness is referring to the whole of the Torah. The Gemara cites pasuk 26 as further proof as it says there:
לקח את ספר התורה הזה ושמתם אותו מצד ארון ברית ה’ אלוקיכם והיה שם בך לעד
Take this Book of the Torah and put it at the side of the Ark of the Covenant of Hashem your G-d that it remain there as a witness upon you.
In this pasuk there is an explicit reference to the complete Torah as the witness.
The Rambam adds an additional reasoning. The directive that we cannot write a Torah in a disconnected fashion, “אין כותבין התורה פרשיות פרשיות” – one does not write the Torah section by section – doesn’t allow us to write Parshat HaAzinu alone. The commandment to write HaAzinu automatically implies writing the Torah in its entirety.
Everyone seems to agree that the words “write for you this song” are an implied reference to the whole of the Torah. The question then arises, why refer to the Torah as “song”? Obviously there are parts of the Torah that are song and written in poetic form, but most of the Torah is not. Most of the Torah is prose. Why then call the Torah “song”?
According to Rav Kook, song is the expression of a broader and deeper perception of the events of life. Song gives expression to a deeper dimension that exists in the familiar, regular, mundane human experience. It speaks of the significance of events, their place in the bigger picture, the meaning behind the seemingly insignificant (Rav Kook, Olat R’aya 1. P. 200). Technically song, in the musical sense, also strings together individual notes and words to create one coherent harmonious product.
All of the Torah is called Song because the Torah comes to give us a different perspective, a higher perspective on all the aspects of life in this world – a perspective that gives everything its’ significance in the whole, a perspective that allows us to set goals based on the deeper and more meaningful side of life. A perspective that connects the insignificant in our lives to the overall Tikkun Olam.
שנזכה אמן כן יהי רצון