Multiplication As Spiritual Elevation
והרבך וברך פרי בטנך
The pasuk states, "And He will multiply you, and He will bless the fruit of your womb" (Devarim 7:13).
The Sfas Emes opens with the pasuk that promises both that Hashem will multiply Bnei Yisrael and that He will bless the fruit of their womb.
קשה דהיינו הך
This is difficult, for the two expressions appear to be one and the same.
He raises a difficulty: since blessing the fruit of the womb already means increasing the people's numbers, the phrase "He will multiply you" seems to add nothing.
וי"ל כמ"ש רש"י הרבה אתכם הרים אתכם
And one may answer in accordance with what Rashi writes, that "He will multiply you" means "He will raise you up."
He answers by citing Rashi, who explains that "He will multiply you" does not refer to numerical increase but rather means that Hashem will raise Bnei Yisrael up.
שהרבך הוא התרוממות:
For "He will multiply you" denotes an elevation and exaltation.
Thus the first phrase speaks of a loftiness and exaltation of Bnei Yisrael, which is a distinct blessing from the increase in numbers conveyed by the fruit of the womb.
Summary: The Sfas Emes examines the pasuk "And He will multiply you, and He will bless the fruit of your womb" (Devarim 7:13) and asks why both phrases are needed, since each seems to describe the same increase of Bnei Yisrael. Drawing on Rashi, he answers that "He will multiply you" does not mean numerical growth at all, but rather that Hashem will raise Bnei Yisrael up. The word therefore signals an elevation and exaltation of the people, a spiritual loftiness that stands apart from the physical increase promised in the blessing of the fruit of the womb. In this way the two phrases convey two separate berachos rather than a single redundant one.