World entrusted to Bnei Yisrael

ארץ יראה ושקטה בתחלה יראה כו' כדר"ל תנאי התנה כו'.

"The earth feared and was still" — at first it feared, etc., as Reish Lakish said: He (Hashem) made a condition, etc.

The Sefas Emes cites the pasuk (Tehillim 76:9) and the teaching of Reish Lakish that at Creation Hashem made a condition with the works of Bereishis — that they would endure only if Bnei Yisrael would accept the Torah. Hence the earth "feared" until Mattan Torah.

וקשה דא"כ היראה הי' כל הדורות שלא ניתנה התורה ובקרא כתיב משמים השמעת דין ארץ יראה כו'.

And this is difficult: if so, the fear would have lasted through all the generations during which the Torah had not yet been given — yet in the pasuk it is written, "From heaven You made judgment heard; the earth feared and was still."

The difficulty: the verse implies a single moment when the earth's fear was stilled, but if everything hung on the giving of the Torah, the earth should have remained in suspense throughout all the generations before Sinai.

אך הדורות שמקודם היו ניזונין בחסדו של מקום ב"ה כדאיתא בגמ' כ"ו כי לעולם חסדו נגד כ"ו דורות שבב' אלפים תוהו כו'.

But the earlier generations were sustained by the chesed of HaMakom (the Omnipresent), blessed is He, as is brought in the Gemara: the twenty-six "Ki le'olam chasdo" (For His kindness is forever) correspond to the twenty-six generations of the two thousand years of tohu (formlessness).

The generations before Mattan Torah were carried purely by Hashem's chesed — pure gift, not earned. The twenty-six refrains of "Ki le'olam chasdo" in Hallel correspond to those twenty-six generations from Adam to Moshe Rabbeinu, who were sustained by undeserved kindness.

אך בעת נתינת התורה והמצות נמסר אז כל הנהגת העולם ביד בנ"י.

But at the time of the giving of the Torah and the mitzvos, the entire conduct of the world was then handed over into the hands of Bnei Yisrael.

At Sinai the world shifted from being run by chesed alone to being entrusted to Bnei Yisrael — now the world's continued existence would depend on their avodah.

בעשותם מצות התורה מתקיים הבריאה.

Through their performing the mitzvos of the Torah, the Creation is sustained.

From Mattan Torah onward, the survival of the world rests on Bnei Yisrael keeping the mitzvos — their deeds uphold all of Creation.

ולכן אז יראה כיון שנמסרה ביד בו"ד:

And therefore at that time it "feared," since it was handed over into the hands of flesh and blood.

This resolves the difficulty: the earth's "fear" was specifically at Mattan Torah, because only then did the responsibility for the world's survival pass into human hands — and with that weight came the trembling. Before that, under pure chesed, there was no such fear.

Summary: Before Mattan Torah the world was carried by Hashem's pure chesed, so there was no "fear." At Sinai the conduct of Creation was placed into the hands of Bnei Yisrael, whose mitzvos now sustain the world — and it was precisely this transfer of responsibility to flesh and blood that caused the earth to "fear and be still."