From Servant To Son
בפרשת המלחמה כי תצא למלחמה כו' וראי' כו' עם רב כו' ל"ת מהם כו' ה"א עמך המעלך מא"מ
In the parsha of war, "When you go out to war against your enemies, and you see [horses and chariots,] a people more numerous [than you, do not fear] them, [for] Hashem your God is with you, who brought you up out of the land of Egypt" (Devarim 20:1).
The Sfas Emes opens with the Torah's command about going to war: even against a vastly larger enemy, Bnei Yisrael need not fear, since Hashem who took them out of Egypt is with them.
ואח"כ כ' וקראת אלי' לשלום ובמד' דורש על מרע"ה ותגזר אומר ויקם שיהי' קריאה לשלום
And afterward it is written, "and you shall call out to it for peace" (Devarim 20:10), and in the Midrash it is expounded regarding Moshe Rabbeinu, "You will decree a matter and it will be fulfilled" (Iyov 22:28) — that there should be a calling out for peace.
Right after the war command, the Torah requires offering peace first, and the Midrash links this power of decreeing peace to Moshe Rabbeinu.
והענין הוא כי בנ"י שיצאו מא"מ להיות צבא מלחמה להלחם עם אויבי ה' כמ"ש יצאו כל צבאות ה'
The matter is thus: Bnei Yisrael who went out from the land of Egypt to be an army of war, to wage battle against the enemies of Hashem, as it is written, "all the legions of Hashem went out [from the land of Egypt]" (Shemos 12:41).
He explains that Bnei Yisrael left Egypt as Hashem's army, organized to fight His enemies.
וכתי' וחמשים עלו מזוינים זה הכח נטלו בנ"י ביצ"מ שנק' עבדי ה' ללחום מלחמות ה'
And it is written, "and the Bnei Yisrael went up armed [out of the land of Egypt]" (Shemos 13:18) — this power Bnei Yisrael received at the Exodus from Egypt, for they are called the servants of Hashem, to wage the wars of Hashem.
This warrior power came to them specifically at the Exodus, when they became the servants of Hashem charged with waging His wars.
אך בקבלת התורה זכו בנ"י לבחי' בנים ובזה הכח יכולין לקרב מן האומות הראוים לזה וזה כח התורה עוז לעמו יתן יברך א"ע בשלום
But through the receiving of the Torah, Bnei Yisrael merited the level of sons, and with this power they are able to draw close those among the nations who are fit for this, and this is the power of the Torah: "Hashem will give might to His people, Hashem will bless His people with peace" (Tehillim 29:11).
At Matan Torah, however, they rose to the higher level of sons, and that level gives them the power to draw fitting members of the nations close in peace.
כמ"ש בורא ניב שפתים כו' שלום לרחוק ולקרוב לכן מייחס זה הכח אל מרע"ה שר התורה
As it is written, "[I] create the speech of the lips [Hashem says:] Peace, peace, to the far and to the near" (Yeshayahu 57:19) — therefore this power is attributed to Moshe Rabbeinu, the prince of the Torah.
The verse about creating peaceful speech shows that this power of peace belongs to Moshe Rabbeinu, the prince of the Torah.
ובאמת עבד מוכן למלחמת המלך ואין בידו לחדש דבר
And in truth, a servant is prepared for the war of the king, but it is not in his hand to introduce anything new.
A servant can only carry out the king's war as he was commanded; he has no authority to innovate or change anything.
אבל בן יכול לקרב מי שרוצה
But a son is able to draw close whomever he wishes.
A son, by contrast, has the standing to bring close whomever he chooses.
וב' הכחות האלו נמסרו לבנ"י ביצ"מ ובקבלת התורה
And these two powers were given over to Bnei Yisrael at the Exodus from Egypt and at the receiving of the Torah.
These two distinct powers — the servant's war and the son's peace — were granted at the Exodus and at the receiving of the Torah respectively.
וב' אלו יש מהם בכל איש ישראל והם בחי' ימי המעשה בחי' עבד
And both of these are found in every individual of Yisrael, and they are the aspect of the weekday days, the aspect of a servant.
Every individual of Yisrael carries both: the weekday corresponds to the level of a servant.
וש"ק יום מנוחה ושלום בחי' בן כנ"ל:
And the holy Shabbos is a day of rest and peace, the aspect of a son, as explained above.
Shabbos, a day of rest and peace, corresponds to the higher level of a son.
Summary: The Sfas Emes contrasts two spiritual powers that Bnei Yisrael received. At the Exodus they became the servants of Hashem, an army equipped to wage the wars of Hashem against His enemies, but a servant can only carry out his orders and cannot innovate. At Matan Torah they rose to the level of sons, gaining the power of peace — the ability to draw close those of the nations who are fit, just as a son may bring near whomever he wishes. This power of peace is bound up with Moshe Rabbeinu, the prince of the Torah. Both levels live within every Jew: the weekday is the aspect of the servant, while the holy Shabbos, a day of rest and peace, is the aspect of the son.