In considering which parsha should be read on the Shabbos preceding Shavuos, one might think that the previous parsha, B’chukosai, which ends with the words, “These are the commandments which G-d commanded Moshe for the Children of Israel, on Mount Sinai” would be appropriate. Yet, the custom is even to connect the readings of B’har with B’chukosai (if necessary) so that parshas Bamidbar - not B’chukosai - will precede Shavuos. The L'vush (Chur, 428) explains that this is in order to separate the curses of B'chukosai from the celebration of receiving the Torah.
In other words, according to the L’vush, the reading of Bamidbar precedes Shavuos not because its reading is appropriate, but because B’chukosai contains an unappropriate element. But, with the following textual analysis, it becomes apparent that Bamidbar is a fitting reading as a lead-on to Shavuos.
Bamidbar begins, “And G-d spoke to Moshe in the Sinai desert, in the Tent of Meeting - on the first day of the second month in the second year of their exodus from Egypt - saying:” (1:1)
For this verse to detail the geographical location of where G-d spoke to Moshe (“in the Sinai desert”) seems unnecessary. We know that G-d spoke to Moshe in the Sinai desert, for the Torah specifically records that it was nineteen days after this parsha was said, that Klal Yisroel traveled out of this desert (Bamidbar, 10:11).
But the verse intends a deeper understanding to the words, “in the Sinai desert”. We find, regarding the conditions under which G-d gave the Torah to the Jews, the verse “He found them in a desert” (D'varim, 32:10). But did G-d indeed find them in a desert? It was G-d who led them there! Rather, the Torah informs us that Klal Yisroel, regardless of geographical location, needs a desert “frame of mind” if they are to receive Torah. “He found them (feeling as if they were) in a desert” - despite their enjoying the pillar of fire, pillar of cloud, manna, and other such miraculous benefits. Only when Klal Yisroel came to understand that, without the Torah, they were barren as “a desert”, only when “He found them in” such a state of understanding - did He give them the Torah
This is the intention of our verse, too. The Torah is not emphasizing that Moshe Rabbenu was in a desert, but that G-d spoke to him ‘because’ he had a desert frame of mind.
The more we realize our need for Torah and the more we understand that without Torah we are like an empty desert - the more Torah we are able to receive and absorb into our hearts. (Sfas Emes, Bamidbar, 5637)
When we celebrate the Yom Tov of Shavuos (or any Yom Tov), we are not only marking a past historical event. The metaphysical event is actually occurring “now”, and we are able to absorb its light and gain new degrees of its holiness. Therefore, we should prepare as we prepared before for the original receiving of the Torah, at Mount Sinai. By reading this parsha, we are reminded yet again that without Torah we are a barren wasteland - a mindset which readies us for Shavuos.
To gain the benefits of Shavuos (and of all Yom Tovim), it is all-important that we enter the Yom Tov prepared. As explained above, procurement of a desert mind-set is an important preparation for Shavuos. But it is not the only preparation. Rav Yitzchok Yaakov Ruderman, zt”l, Rosh Yeshiva of Yeshivas Ner Yisroel, had the following custom. He reasoned (based on ‘chazal’), that the more Torah he would learn before Shavuos, the more benefit he would have from the lights and holiness which emanate on Shavuos. Therefore he learned through all of ‘shas’ during the 49 day period of ‘sfira’. Thus prepared, he entered Shavuos.