Torah depends on Bnei Yisrael

דבר אתה עמנו כו' פן נמות כו'.

"You speak with us… lest we die," etc.

At Sinai Bnei Yisrael said to Moshe Rabbeinu, "You speak with us… but let Hashem not speak with us, lest we die" (Shemos 20:16).

וקשה כי בנ"י מסרו נפשם בעבור התורה ומאי פן נמות.

And this is difficult, for Bnei Yisrael gave over their very lives for the sake of the Torah — so what is meant by "lest we die"?

The question: Bnei Yisrael were ready to be moser nefesh for Torah, so why would they suddenly fear death and ask Moshe to be the intermediary?

אבל באמת מתחילה לא האמינו כל כך להיות התורה תלוי בהם ממש והיו שפלים בעיניהם וכאשר קיבלו התורה נתקרבו נפשותם למקור שורשם ואחיזתם בתורה וראו עין בעין כי אורייתא וקוב"ה וישראל כולהו חד.

But in truth, at first they did not so fully believe that the Torah literally depends on them, and they were lowly in their own eyes; and when they received the Torah, their souls were drawn close to the source of their root and their grasp in the Torah, and they saw with their own eyes that the Torah, the Holy One, and Bnei Yisrael are all one.

Initially, in their humility, Bnei Yisrael did not realize that Torah's very existence rests upon them. Once they received it, their souls reconnected to their root and they perceived clearly the truth that "Oraisa, Kudsha Brich Hu, v'Yisrael — kulhu chad," Torah, Hashem, and Yisrael are one (cf. Zohar).

ולכן חששו פן נמות ויתבטל ח"ו התורה כאשר חכמים הגידו כי התורה ביקשה עליהם כו':

And therefore they feared "lest we die," and the Torah would, chas v'shalom, be nullified — as the Chachamim related that the Torah pleaded on their behalf, etc.

Their fear was not for themselves but for the Torah: realizing Torah depends on Bnei Yisrael, they worried that if they died from the overwhelming revelation, the Torah itself would have no one to uphold it. Chazal (Shabbos 88b) teach the Torah interceded so they would survive to receive it.

Summary: When Bnei Yisrael asked Moshe to intercede "lest we die," they were not retreating from mesirus nefesh. Having grasped at Sinai that Torah, Hashem, and Yisrael are one and that the Torah literally depends on them, they feared that their death would, chalilah, leave the Torah with no one to sustain it.