Purim repairs the sin of the Egel

ואיתא הדר קבלוה בימי אחשורוש כו'.

It is taught: they accepted it anew (hadar kibluha) in the days of Achashverosh, etc.

The Gemara (Shabbos 88a) says Bnei Yisrael re-accepted the Torah willingly in the time of the Purim miracle.

ותוס' הקשו הא הקדימו נעשה לנשמע.

And Tosafos raised a difficulty: but they had already placed "we will do" before "we will hear" (naaseh before nishma)!

Tosafos asks: at Har Sinai Bnei Yisrael already embraced the Torah wholeheartedly with "naaseh ve-nishma," so what was left to accept anew?

אבל יראה כי ע"י חטא העגל אבדו נעשה כדאיתא במדרש הזהרו בנשמע.

But it appears that through the sin of the Egel (Golden Calf) they lost the "naaseh," as the Midrash says: be careful with the "nishma."

The cheit ha-Egel forfeited the level of "naaseh" — the unconditional commitment to action — leaving them only with "nishma," the receptivity of hearing.

ואעפ"כ הי' לבנ"י עמידה אחר החטא.

And even so, Bnei Yisrael had a standing (amidah) after the sin.

Despite the fall of the Egel, Bnei Yisrael still retained a foothold — they did not lose everything.

וזה הי' ענין כפה עליהם ההר.

And this is the matter of "He held the mountain over them" (kafah aleihem har).

The image of Hashem holding Har Sinai over them like a barrel expresses this remaining bond — a commitment that holds even when their own "naaseh" had slipped.

שאף כשיאבדו ח"ו הקדמת נעשה כו' רק הרצון והשמיעה יהי' כראוי.

That even when they would lose, chas ve-shalom, the precedence of "naaseh," etc. — so long as the ratzon (will) and the "nishma" (hearing) remain as they should —

Even should the active "naaseh" be lost, as long as the inner will and the receptivity of "nishma" stay intact, the bond is not broken.

יסייעו להם משמים לגוף המעשה.

they would be assisted from Shomayim with the body of the deed itself.

Hashem pledged that He would supply Heavenly help for the actual performance — the "naaseh" — wherever their own strength fell short. This is the deeper meaning of holding the mountain over them.

והדר קבלוה בימים האלו.

And they accepted it anew in these days.

This renewed acceptance is what took place in the days of Purim.

כמ"ש קימו וקבלו כו' להיות עושים כו'.

As it is written: "they fulfilled and accepted... to be doing," etc.

The pasuk in Megillas Esther (9:27) "kiyemu ve-kiblu... to be doing" signals the restoration of the active "naaseh" that had been lost.

א"כ נראה שנתקן.

If so, it appears that it was repaired.

The lost "naaseh" was now mended and restored.

חטא העגל בנס דפורים.

The sin of the Egel was rectified through the miracle of Purim.

The tikkun for the Golden Calf was completed specifically through the nes of Purim.

והאמת כי כל חטא העגל בא על ידי הרשע עמלק אשר עירבב אותנו קודם קבלת התורה וזרק ארס ושאור בעיסה.

And the truth is that the entire sin of the Egel came about through the wicked Amalek, who confused us before kabbalas haTorah and cast venom and leaven into the dough.

The root of the cheit ha-Egel traces back to Amalek, who attacked and unsettled Bnei Yisrael on the way to Sinai, injecting poison and a corrupting "leaven" of doubt into the nation.

לכן כפי מחיית עמלק נתקן זה החטא כנ"ל:

Therefore, to the extent of the blotting out of Amalek, this sin is rectified, as above.

Since Amalek caused the fall, the undoing of Amalek — accomplished through Purim — is precisely what heals the wound of the Egel.

Summary: At Sinai Bnei Yisrael placed "naaseh" before "nishma," but the sin of the Golden Calf cost them the "naaseh." "He held the mountain over them" was Hashem's pledge that even if their active commitment failed, He would supply Heavenly help for the deed itself as long as their will and "nishma" remained. The damage, rooted in Amalek's interference before Sinai, was finally repaired through the renewed acceptance of Torah at Purim — the blotting out of Amalek mending the sin of the Egel.