On this basis, we can understand the meaning of the verse, “On this day, they came to the Sinai desert.”וְזֶהוּ בַּיּוֹם הַזֶּה בָּאוּ מִדְבַּר סִינָי,
The maamar in Torah Or explainsוּמְבָאֵר בְּתוֹרָה אוֹר,
that the word midbar shares the same root as the word dibbur, meaning “speech.”דְּמִדְבָּר הוּא מִלְּשׁוֹן דִּבּוּר,
Midbar adds a mem to the root dalet-beis-reish, thus reading medabeir.וְנִקְרָא מִדְבָּר בְּתוֹסֶפֶת מ'
(The letter mem is one of the letters alluded to in the mnemonic הֶאֱמַנְתִּי"ו.)(דְּמ' הוּא מֵאוֹתִיּוֹת הֶאֱמַנְתִּי"ו
When one of the letters of that mnemonic is appended to a word as prefix or a suffix, it limits the scope of the application of the root word.)1 For example, the term מהבית, “from the house,” implies not the house itself, but something from it.שֶׁמּוֹרִים עַל הַקְטָנַת הָעִנְיָן)
With regard to the term midbar, in a spiritual sense, the limitation alluded to by the prefix mem indicates that the person’s speech is characterized by bittul.לְהוֹרוֹת שֶׁהַדִּבּוּר הוּא בְּבִטּוּל.
[This concept also relates to a desert in a literal sense.[וְעִנְיָן זֶה שַׁיָּךְ גַּם לְמִדְבָּר כִּפְשׁוּטוֹ,
A desert is described2 as “an unsown land.”אֶרֶץ לֹא זְרוּעָה,
When a person’s speech is a product of his own thought and will,דִּכְשֶׁהַדִּבּוּר הוּא עַל פִּי שִׂכְלוֹ וּרְצוֹנוֹ,
his thought and will are the “seeds”הַשֵּׂכֶל וְהָרָצוֹן הֵם הַזְּרִיעָה
that enable his speech to sprout forth.שֶׁעַל יְדֵי זֶה הוּא צְמִיחַת הַדִּבּוּר.
According to this understanding, the concept of a desert being “an unsown land” meansוְעִנְיַן מִדְבָּר אֶרֶץ לֹא זְרוּעָה הוּא
that the words of Torah that a person speaks are the words of G‑d,שֶׁהַדִּבּוּר דְּתוֹרָה שֶׁמְּדַבֵּר הוּא דְּבַר ה'
i.e., they are not sown by his own thoughts or will.3]וְאֵינוֹ זָרוּעַ מִשִּׂכְלוֹ וּרְצוֹנוֹ].
With regard to prophecy, it is written:4 “And I will place My words in your mouth.” When a prophet would speak, he would not speak his own words. Rather, it was G‑d speaking through him. In a similar vein, when a Jew speaks words of Torah, the words are not the product of his own thoughts or desires but rather, they are G‑d’s words.
The maamar in Torah Or then focuses on the name Sinai. Based on the phonetic relationship between that name and the word sinah, “enmity,” our Sages state5 that through the Giving of the Torah, “enmity (sinah) descended to the nations of the world.”וְסִינַי הוּא שֶׁיָּרְדָה שִׂנְאָה לְאֻמּוֹת הָעוֹלָם,
In this vein, the Torah is referred to6 as תּוּשִׁיָּה.וְהוּא שֶׁהַתּוֹרָה נִקְרֵאת תּוּשִׁיָּה
Our Sages note7 that תש, the root of that word, also means “weakness,” and state that Torah study “weakens a person’s power.” The inner intent of our Sages’ teaching is not that the Torah weakens a person’s physical well-being, but
that it weakens the power of the sitra achra, the kabbalistic term for all that is not holy.לְפִי שֶׁמַּתֶּשֶׁת כֹּחַ הַסִּטְרָא אַחֲרָא.
It is possible to say that the two terms, midbar and Sinai, can be associated with the two preparatory stages for the Giving of the Torah explained above:וְיֵשׁ לוֹמַר,
The fact that “on this day” the Jewish people “entered a desert,” a midbar, which, as explained above, connotes bittul,דְּזֶה שֶׁבַּיּוֹם הַזֶּה בָּאוּ מִדְבָּר
is because “on this day,” (Rosh Chodesh,) the moonהוּא לְפִי שֶׁבַּיּוֹם הַזֶּה (רֹאשׁ חֹדֶשׁ) הַלְּבָנָה
[and, thus, the Jewish people who establish their calendar according to the moon,][וְכֵן יִשְׂרָאֵל שֶׁמּוֹנִין לַלְּבָנָה]
shines merely as a point, i.e., is characterized by bittul.הִיא נְקֻדָּה בִּלְבָד,
The fact that “on this day” they arrived at Sinai, i.e., that enmity descended to the yetzer hara,8וְזֶה שֶׁבַּיּוֹם הַזֶּה בָּאוּ סִינַי שֶׁיָּרְדָה שִׂנְאָה לַיֵּצֶר הָרָע
is because on this day (Rosh Chodesh Sivan),הוּא לְפִי שֶׁבַּיּוֹם הַזֶּה (רֹאשׁ חֹדֶשׁ סִיוָן)
the refinement of the fundamental emotional qualities of the animal soul was completed, thus enabling the Jews to attain a level of perfection. This involves the rejection – enmity – of the yetzer hara and the character traits associated with it.נִשְׁלָם הַבֵּרוּר שֶׁל עִקְּרֵי הַמִּדּוֹת דְּנֶפֶשׁ הַבַּהֲמִית.

Summary

The word midbar shares the same root as the word dibbur, “speech.” The prefix mem indicates that the person’s speech is characterized by bittul. This concept is also reflected in the description of a desert as “an unsown land .” When a person speaks as a result of his own thought and will, his thought and will sow the seeds from which his speech sprouts forth. When a person speaks words of Torah, the words are not the products of his own thoughts or desires. Rather, they are G‑d’s words.
The maamar in Torah Or then focuses on the word “Sinai,” quoting our Sages, who understand it as implying that through the Giving of the Torah, “enmity” of the forces opposed to holiness “descended” from Above. This facilitates our Divine service of refining our emotional qualities during the Counting of the Omer.
Thus, in mentioning “the Sinai desert” the verse is referring to the two preparatory stages necessary to receive the Torah: a) bittul, “the desert”; and b) shleimus, the refinement of the emotions alluded to by the name “Sinai.”