In honor of Yechiel Shulman’s bar mitzvah, I’m going to go present something from his uncle’s sefer, ישמח אב on ברכות and פסחים. It’s the introduction to that sefer.
We start with the introduction to מעמד הר סיני:
The statement וגם בך יאמינו לעולם is the reason we believe the Torah will never be replaced or overridden:
What makes Moshe’s נבואה different? What gives מתן תורה its authority?
First, what is the basis of the authority of any נביא?
Rav Shulman asks:
If Moshe is a נביא, then all the laws that he said should be under the rule of אליו תשמעון and therefore every commandment should carry a penalty of מיתה בידי שמים. Didn’t honor your parents? Death! Didn’t put a railing on your rooftop terrace? Death! Ignored your enemy’s staggering donkey? Death!
To understand the Brisker Rav, we have to look at the laws of נבואה. How does one become a certified prophet, one whom everyone else has to listen to?
That’s a certified נביא; someone who:
is an acknowledged holy person in learning and in action
is ascetic, separate from worldly matters (מהלך בדרכי הנבואה ובקדושתה ופרישותה); what in תנ״ך is called a בן נביא
does some kind of miraculous sign
claims a message from G-d that does not contradict the Torah
Such a person must be obeyed on pain of מיתה בידי שמים.
The Brisker’s point is that Moshe, despite his level of נבואה and despite all the signs and wonders of יציאת מצרים, was not a certified נביא. What he said was not a חפצא של נבואה:
Before מעמד הר סיני, Moshe did signs, and the people believed he was in fact sent by ה׳ (ויאמינו בה׳ ובמשה עבדו), but it wasn’t for the purpose of making the people obey him:
Moshe is not part of the entire מצוה of נביאים, אליו תשמעון; that’s why there’s no law of מיתתן בידי שמיים. We don’t listen to the Torah because of Moshe’s prophecy.
The faith they had in Moshe before מעמד הר סיני did not obligate them in any laws:
We see this in that nobody dies (at least not the Jews) in פרשת בשלח. בני ישראל complain and rebel over and over and ה׳ gets angry but never punishes. It’s not like ספר במדבר, where we see one plague after another. Even though they had laws before מעמד הר סיני:
And this is implied in Rashi in this week’s parasha:
Moshe is משה רבינו, not משה הנביא. A נביא only has the authority to declare a הוראת שעה, not to create some new legislation. This is connected to the inherent source of the נביא's authority:
So all signs and wonders of יציאת מצרים were not to validate Moshe, but to demonstrate to בני ישראל and to the world G-d’s power and authority.
The Ramban at end of בא famously discusses how many of the mitzvot are in order to remember יציאת מצרים. So rather than the signs validating Moshe’s prophecy, Moshe’s prophecy serves to validate the signs of יציאת מצרים:
And this is what we heard directly from הקב״ה at סיני: