Pesach and milah as twin covenants

ובי"ד היו מקיימין בנ"י ב' מצות דם פסח ודם מילה והם ב' המצות שחייבין עליהם כרת משא"כ בשום מ"ע אחרת.

And on the fourteenth [of Nissan] Bnei Yisrael would fulfill two mitzvos — the blood of the Pesach and the blood of milah — and these are the two mitzvos for [neglecting] which one is liable to kares (excision), unlike any other positive commandment.

The Sefas Emes points to the unique status of korban Pesach and bris milah: alone among all positive mitzvos, failing to perform them carries the penalty of kares, marking them as the two foundational obligations.

שהם עיקר המצות שעל ידיהם זכו בנ"י אח"כ לתורה.

For they are the primary mitzvos through which Bnei Yisrael afterward merited the Torah.

These two mitzvos, performed at the time of the Exodus, were the merit by which Bnei Yisrael became worthy to receive the Torah at Sinai.

וכתיב לא בשמים היא כו' מי יעלה לנו כו' ולא מעבר לים כו' קרוב כו' הדבר כו' בפיך ובלבבך כו'.

And it is written: "It is not in Heaven… who shall ascend for us… nor is it across the sea… the matter is very close… in your mouth and in your heart," etc.

The Sefas Emes brings the verses describing the Torah as near and accessible — not in the heavens or across the sea, but "in your mouth and in your heart."

ורמזו ר"ת מיל"ה.

And they hinted that the initial letters [of these phrases] spell milah.

The first letters of "Mi ya'aleh Lanu ha'shamayim" allude to the word milah — bris milah is woven into the Torah's accessibility.

וי"ל עוד ולא מעבר לים הרמז על מצות פסח ויציאת מצרים.

And one may further say that "nor is it across the sea" is a hint to the mitzvah of Pesach and the Exodus from Mitzrayim.

The phrase "across the sea" evokes Krias Yam Suf and the redemption from Mitzrayim, linking the verse to the Pesach.

וב' אלו הם בחי' בפיך ובלבבך.

And these two [mitzvos] are the aspects of "in your mouth and in your heart."

Pesach and milah correspond to the two phrases "in your mouth" and "in your heart," the two faculties through which Torah becomes part of a person.

פסח. פה סח. ברית הלשון.

"Pesach" — [read as] "peh sach" (the mouth speaks) — the bris (covenant) of the tongue.

The Sefas Emes parses "Pesach" as "peh sach," the mouth that speaks, identifying it with the covenant of the tongue — "in your mouth."

והוא בחי' תורה שבע"פ.

And this is the aspect of Torah she'baal peh (the Oral Torah).

The covenant of the mouth corresponds to the Oral Torah, transmitted by speech.

ומילה בלבבך ברית המעור.

And milah is "in your heart" — the covenant of the flesh (bris hama'or).

Bris milah, sealed in the body, corresponds to "in your heart," the inner covenant of the flesh.

והוא בחי' תורה שבכתב במה שחתם בריתו בבשרנו.

And this is the aspect of Torah she'biksav (the Written Torah), in that He sealed His covenant in our flesh.

Milah, the fixed covenant engraved permanently in the body, parallels the Written Torah, which is permanent and inscribed.

וע"ז איתא שכל אדם צריך להיות לו ב' אותות.

And regarding this it is taught that every person needs to have two signs (osos).

Building on this, the Sefas Emes notes the teaching that a Jew must always bear two "signs" of his covenant with Hashem.

בחול מילה ותפילין.

On weekdays: milah and tefillin.

During the week, the two signs are bris milah and tefillin.

ובשבת מילה ושבת.

And on Shabbos: milah and Shabbos.

On Shabbos, when tefillin are not worn, Shabbos itself serves as the second sign alongside milah.

כי תפילין. ושבת הכל זכר ליציאת מצרים.

For tefillin and Shabbos are all a remembrance of the Exodus from Mitzrayim.

Both tefillin and Shabbos commemorate Yetzias Mitzrayim, tying them to the Pesach.

בחי' הפסח כו' תורה שבע"פ שורש המצות.

[They are] the aspect of the Pesach, etc. — Torah she'baal peh, the root of the mitzvos.

Tefillin and Shabbos belong to the Pesach/Oral Torah dimension, which is the root from which the mitzvos grow.

ולכן צריך לעבור השבת על הקטן קודם שנימול שאות שבת ותפילין הכנה לאות המילה כנ"ל:

Therefore Shabbos must pass over the infant before he is circumcised — for the sign of Shabbos and tefillin is a preparation for the sign of milah, as above.

A baby boy must live through at least one Shabbos before his bris on the eighth day; the Sefas Emes explains that the "Pesach-type" signs of Shabbos and tefillin (Oral Torah, the root) serve as preparation for the "milah-type" sign (Written Torah, the seal).

Summary: The blood of Pesach and the blood of milah — the only two positive mitzvos whose neglect carries kares — were the merit by which Bnei Yisrael became worthy of the Torah. The verse "it is not across the sea… in your mouth and in your heart" alludes to both: Pesach as "peh sach," the covenant of the mouth and the Oral Torah, and milah as the covenant of the flesh and the Written Torah. Every Jew bears two signs of this covenant — milah with tefillin during the week, milah with Shabbos on Shabbos — and a child must first experience Shabbos, the "Pesach-type" preparation, before receiving the sign of milah.