The Gemara in Masechet Shabbat relates the following regarding the timing of Matan Torah:
It was taught in a braita, there were three things that Moshe did on his own initiative and Hashem concurred with his decision. 1) He added a day [of preparation before Matan Torah] on his own initiative 2) He separated from his wife 3) He broke the luchot.
He added a day on his own initiative, how did he expound? (He was told) “And prepare yourselves today and tomorrow;” just as “tomorrow” includes the night which precedes it, so too “today” must include the night which precedes it, and the night of “today” has already passed. One may infer from this that there need to be two days aside from today. And from where do we know that Hashem concurred with his decision? From the fact that the Shechinah did not descend until the morning of Shabbat.
Day and Night
As we know, with regard to bnei Noach, the night follows the day, as it says (Bereishit 8:22) “וְיוֹם וָלַיְלָה לֹא יִשְׁבֹּתוּ — and day and night shall not cease.” This is not the case with Bnei Yisrael, who operate in accordance with the original plan for the world, which is (ibid. 1:5) “וַיְהִי עֶרֶב וַיְהִי בֹקֶר יוֹם אֶחָד — it was evening and it was morning; one day.” And this is indeed fitting, since Chazal tell us that it was “בשביל ישראל שנקרא ראשית — it is only for Yisrael who are called ‘reishit’ that the world was created.”
From the time of the chet of Adam HaRishon, mankind was demoted from the level of “וַיְהִי עֶרֶב וַיְהִי בֹקֶר” to the level of “וְיוֹם וָלַיְלָה,” until the time when Bnei Yisrael received the Torah and were once again capable of functioning on the level of “וַיְהִי עֶרֶב וַיְהִי בֹקֶר.”
On the fourth of Sivan, Hashem instructed Moshe “וְקִדַּשְׁתָּם הַיּוֹם וּמָחָר — prepare them today and tomorrow.” (Shemot 19:10). That instruction was said at a time when the people had already left the status of Bnei Noach and attained the status of “Yisrael.” Therefore, in keeping with their new status, it was clear to Moshe that “hayom” and “machar” both included the nights that preceded them, as befitting Bnei Yisrael.
Darshening the Spoken Word of Hashem
Perhaps we may suggest an additional, deeper, reason as to why Moshe needed to receive validation from Hashem regarding his drashah. We have mentioned that according to Rashi the first “sefer” of Torah [the “Sefer HaBrit”] was dictated by Hashem to Moshe on the Fourth of Sivan. This sefer included within it the text of the Torah from Bereishit until the events of that day, including Hashem telling Moshe “וְקִדַּשְׁתָּם הַיּוֹם וּמָחָר,” the words which Moshe was then doresh through a hekesh. However, in terms of pshuto shel mikra it seems clear that those words were said to Moshe by Hashem before they were dictated to him as part of the Sefer HaBrit. If so, then it turns out that the subject of Moshe’s drashah was not the text of the Torah, but Hashem’s Spoken Word! This is something quite remarkable! Is it possible to apply the middot of drash to Torah SheBaal Peh? Surely Torah SheBaal Peh is to be learned, but derashot exist solely within the realm of Torah shebichtav!
We are forced to conclude that the madreigah of Moshe at the time of Matan Torah was such that he was able to hear words spoken to him by Hashem, and intuit which of those words would be written down in the Torah, and in what form.
This process of categorizing words that Hashem spoke to him into Torah shebichtav and Torah shebe'al peh is certainly one that required the haskamah of Hashem, which in this case was indeed forthcoming, “for the Shechinah did not descend until Shabbat morning.”
