Wholeness Through Nullification To Hashem
תמים תהי' עם ה"א כו'
"You shall be wholehearted with Hashem your God" (Devarim 18:13), etc.
The Sfas Emes opens with the pasuk commanding that one be wholehearted and complete with Hashem, which will be the theme of the piece.
כי הקב"ה נק' מלך שהשלום שלו
For the Holy One, Blessed is He, is called the King to whom peace belongs.
He brings the title of Hashem as the King to whom shalom, meaning completeness and peace, belongs.
פי' כי השורש והשלימות והתכלית מכל הדברים הוא בו ית' וזה בחי' מלך שהשלום שלו וכח מלכותו ית' משלים ומנהיג הכל כמ"ש וקונה הכל
The explanation is that the root, the wholeness, and the ultimate purpose of all things is found in Him, may He be blessed. This is the aspect of the King to whom peace belongs, for the power of His kingship, may He be blessed, completes and directs everything, as it is written, "and Who acquires all" (from the blessings recited before Krias Shema).
Wholeness here means shleimus: the source, completion, and final purpose of every created thing rests in Hashem alone, and His kingship is what brings everything to its completion.
וכל הדברים חסרים ואין יכולין לבוא אל השלימות רק בהתקרבותם אליו ית' ולזה מיוחדים בנ"י שיכולין לקבל השלימות מאתו ית' לכן נק' השולמית
All things are lacking and cannot arrive at their wholeness except through drawing close to Him, may He be blessed. For this reason Bnei Yisrael are singled out, in that they are able to receive that wholeness from Him, may He be blessed, and therefore she is called "the Shulamis" (Shir HaShirim 7:1).
Since nothing reaches its full completion on its own, every created thing must draw near to Hashem to become whole; Bnei Yisrael have the unique capacity to receive this completeness, which is why Shir HaShirim calls them the Shulamis, related to shleimus.
ולפי שנחסר זה השלימות בעולם לכן המעוננים וקוסמין מבקשין תחבולות ע"י הכישוף לקבל כח בחכמת הטבע
And because this wholeness is lacking in the world, therefore the soothsayers and sorcerers seek stratagems by means of sorcery in order to draw power through the wisdom of nature.
Because the world feels this lack of wholeness, the sorcerers and diviners try to grab power through magic and manipulating the forces of nature.
ולא זה הדרך לבוא אל השלימות ואדרבא מוסיפין להתחסר
But this is not the path to arrive at wholeness; on the contrary, they only increase the lack.
Such methods can never bring real completeness; in truth they only deepen the deficiency.
רק בנ"י נאמר עליהם תמים תהי' עם ה"א
Only of Bnei Yisrael is it said, "You shall be wholehearted with Hashem your God" (Devarim 18:13).
It is Bnei Yisrael, and only they, of whom the Torah says to be wholehearted with Hashem.
ואדרבא ע"י ביטול כל הדעת והחכמות אליו ית' זוכין אל השלימות כמ"ש התהלך לפני והי' תמים
On the contrary, it is specifically through the nullification of all one's intellect and wisdom before Him, may He be blessed, that one merits wholeness, as it is written, "Walk before Me and be wholehearted" (Bereishis 17:1).
The true path is the opposite of sorcery: by nullifying one's own mind and cleverness before Hashem, one actually attains wholeness, as Avraham was told to walk before Hashem and be whole.
ושבת שנק' שלום הוא סהדותא ע"ז
And Shabbos, which is called "peace" (shalom), is the testimony to this.
Shabbos, called shalom, serves as the standing testimony that wholeness comes only from Hashem.
שע"י שבנ"י מבטלין כל המעשים בש"ק לכבודו ית' זוכין לנשמה יתירה והיא השלימות שמקבלין מאתו ית'
For through Bnei Yisrael nullifying all their actions on the holy Shabbos for His honor, may He be blessed, they merit the neshamah yeseirah (additional soul), and that is the wholeness which they receive from Him, may He be blessed.
By setting aside all melachah on Shabbos for Hashem's honor, Bnei Yisrael receive the neshamah yeseirah, which is precisely the wholeness granted to them by Hashem.
וע"ז ניתקן כל שיר השירים ישקני כו' משכני כו' לקבל השלמה מאתו ית' כמו שהוכנו בנ"י לזה בקבלת התורה:
And regarding this the entire Shir HaShirim was composed, "Let Him kiss me" (Shir HaShirim 1:2), "Draw me" (Shir HaShirim 1:4), etc. — to receive the wholeness from Him, may He be blessed, just as Bnei Yisrael were prepared for this through the receiving of the Torah.
All of Shir HaShirim, with its longing to be drawn close to Hashem, was composed to express this yearning to receive shleimus from Him, the same way Bnei Yisrael were readied for it at Kabbalas HaTorah.
Summary: The Sfas Emes explains the command "You shall be wholehearted with Hashem your God" through the idea that Hashem is the King to whom shalom belongs, meaning that the root and completion of every created thing lies in Him alone. Nothing in the world reaches its true wholeness on its own; it must draw close to Hashem, and Bnei Yisrael are uniquely able to receive this completeness, which is why they are called the Shulamis. The sorcerers and diviners seek wholeness through magic and the forces of nature, but this path only deepens the lack; the real way is the opposite — nullifying one's own intellect before Hashem, as Avraham was told to walk before Him and be wholehearted. Shabbos, called shalom, testifies to this, for by setting aside all melachah for Hashem's honor Bnei Yisrael merit the neshamah yeseirah, which is the very wholeness they receive from Him. So too the longing of Shir HaShirim to be drawn close expresses this yearning to receive shleimus from Hashem, just as Bnei Yisrael were prepared for it at Kabbalas HaTorah.