The eighth day's doubled nature like Shabbos

במד' מחלק יום השמיני לב' ימים.

In the Midrash, the eighth day is divided into two days.

The Sefas Emes notes a Midrash that treats the eighth day of the Mishkan's inauguration as if it were two distinct days.

שהקשה דכ' ויהי ביום כלות משה.

For it raised a difficulty from the verse "And it was on the day that Moshe finished [setting up the Mishkan]."

The Midrash asks why this verse uses "vayehi" — a word that often signals distress or trouble.

ומשני שהמשכן נגנז.

And it answers: because the Mishkan was [destined to be] hidden away.

The note of sorrow is because this Mishkan would eventually be concealed, hinting at the future destruction of the Bais Hamikdash.

הדר פריך מויהי ביום השמיני ומשני שמתו נדב ואביהוא.

It then asks again from "And it was on the eighth day," and answers: because Nadav and Avihu died.

The Midrash finds the same note of distress in "the eighth day," explaining it by the deaths of Aharon's sons Nadav and Avihu on that day.

ובאמת הכל הי' בר"ח ניסן כמ"ש רש"י.

And in truth, all of this occurred on Rosh Chodesh Nissan, as Rashi writes.

Both events — the completion of the Mishkan and the eighth day — actually took place on the very same day, the first of Nissan, as Rashi explains.

והענין הוא כמ"ש חז"ל על יום השבת כי כל מעשיו כפולין לחם משנה זכור ושמור כו'.

And the matter is as Chazal said concerning Shabbos, that all of its features are doubled — the double bread (lechem mishneh), "Remember" and "Guard," etc.

The Sefas Emes compares this to Shabbos, which has a recurring quality of doubling: two loaves, the two commands "Zachor" and "Shamor," and so on.

כי יש בו שלימות העוה"ז והארה עליונה כמו שכ' חז"ל אמרה שבת לכל יש בן זוג כו' כנס"י יהי בן זוגך.

For Shabbos contains both the completeness of this world and a supernal illumination, as Chazal said: Shabbos declared, "Everyone has a partner..." [and Hashem replied] "Knesses Yisrael shall be your partner."

Shabbos has a dual nature: it completes the work of this world while also drawing down a higher light. This is why the Midrash pairs Shabbos with Knesses Yisrael — joining the earthly and the heavenly.

א"כ יורד בש"ק הארה מיום העליון אור שבעת הימים ונחשב השבת לב' מדריגות.

If so, on Shabbos Kodesh there descends an illumination from the supernal day — the light of [all] seven days — and Shabbos is therefore reckoned as two levels.

On Shabbos a higher light, containing the essence of all seven days, descends into the day. Thus Shabbos itself comprises two dimensions — the earthly seventh day and the supernal light shining into it.

כמו כן ביום כלות משה שהוא מדריגה התחתונה ירד בו הארה עליונה ונק' יום השמיני לכן חלקו המדרש לב' ימים.

Likewise, on the day Moshe finished [the Mishkan], which is the lower level, a supernal illumination descended into it, and it is called "the eighth day"; therefore the Midrash divided it into two days.

Just as with Shabbos, this single day held two dimensions: the lower level of completing the Mishkan, and a higher light descending into it, earning it the name "the eighth day." That is why the Midrash treats it as two distinct days.

ובב' המדריגות אומר שלא הי' שמחה שלימה עדיין עד לעתיד ליום שכולו שבת:

And regarding both levels, it says that the joy was not yet complete — until the future, to "the day that is entirely Shabbos."

On both planes — the lower and the higher — the simcha remained incomplete, marked by concealment and loss. Full joy awaits the future world, "the day that is entirely Shabbos," when all will be perfected.

Summary: The Midrash divides the eighth day of the Mishkan's inauguration into two days, finding a note of distress both in "the day Moshe finished" (the future hiding of the Mishkan) and in "the eighth day" (the deaths of Nadav and Avihu), even though both occurred on Rosh Chodesh Nissan. The Sefas Emes explains by analogy to Shabbos, whose features are doubled because it joins the completeness of this world with a descending supernal light. So too this day held both a lower level and a higher illumination — yet on both levels the joy was not yet complete, awaiting the future "day that is entirely Shabbos."