Torah Softens The Heart
בפסוק האזינו השמים כו' יערוף כמטר לקחי כו' ענין משל זה למטר כמ"ש כאשר ירד הגשם והשלג כו' כן יהי' דברי כו'
In the verse "Ha'azinu HaShamayim — Listen, O heavens... yaarof kamatar likchi — may my teaching drip like rain..." (Devarim 32:1-2), the meaning of this comparison to rain is as is written, "For just as the rain and the snow come down... so shall be My word..." (Yeshayahu 55:10-11).
The Sfas Emes opens with Moshe Rabbeinu's song comparing his teaching to rain, and links it to Yeshayahu's image that Hashem's word descends like rain and snow to accomplish its purpose.
כי אנו רואים כי הבריאה צריכה לסיוע מן השמים שתוציא האדמה כחה ע"י הגשם והשלג
For we see that the Creation requires assistance from Heaven, so that the earth should bring forth its strength by means of the rain and the snow.
Rain and snow are the Heavenly help the soil needs to release its latent productive power.
מזה יש לנו ללמוד כי כמו כן האדם צריך סיוע משמים
From this we have to learn that in the very same way a person too requires assistance from Heaven.
The lesson is that a person, like the earth, cannot produce his own potential without help sent down from Heaven.
וכן הוא בתהלים במזמור קמ"ז שחושב כל הפעולות הבאים משמים המכין לארץ מטר כו' השולח אמרתו ארץ כו' משליך קרחו כו' ומסיים מגיד דבריו ליעקב כו'
And so it is in Tehillim, in the mizmor of chapter 147, which enumerates all the workings that come from Heaven — "Who prepares rain for the earth...," "Who sends forth His word to the earth...," "Who casts down His ice...," and which concludes, "He relates His words to Yaakov..." (Tehillim 147:8,15,17-19).
Tehillim 147 lists Hashem's gifts to nature — rain, His word, ice — and then turns to His greatest gift, telling His words to Yaakov, hinting that Torah is the true "rain" from Heaven.
שזה באמת עיקר הכח משמים שבא לישראל והוא התורה ומצות
For this in truth is the essential strength from Heaven that comes to Bnei Yisrael, and it is the Torah and the mitzvos.
That decisive Heavenly strength given to Bnei Yisrael is the Torah and the mitzvos themselves.
וכמו שהאדמה לא תוציא כחה עד שתהי' נעזרת משמים
And just as the earth does not bring forth its strength until it is aided from Heaven,
Setting up the parallel: the earth stays barren until Heaven assists it.
כן לב איש הישראלי צריך עזר בכח התורה (שמרפת) [שמרככת] לב האדם
so too the heart of a Yisrael requires aid through the power of the Torah, which softens the heart of a person.
Likewise a Jew's heart cannot bring forth its good until the Torah's power softens it.
כמ"ש חז"ל אם אבן הוא נימוח כו' ע"י התורה שנקראת מים
As Chazal said, "Even if a person is as hard as a stone, he is dissolved..." — through the Torah, which is called water.
Chazal teach that even a heart hard as stone is dissolved by Torah, which is compared to water that wears down stone.
וכמו כן הוא מעביר קשיו' ערפו של היצה"ר שלכן יערוף כולל ג"כ לשון הריגה כמ"ש בספרי:
And in the very same way it removes the hardness of the "stiff neck" (orf) of the yetzer hara, which is why "yaarof" also includes the connotation of killing, as is stated in the Sifri.
Torah also breaks the "stiff neck" of the yetzer hara — and the word "yaarof" itself carries a sense of killing, as the Sifri brings, meaning Torah slays the evil inclination.
Summary: The Sfas Emes builds on the opening verse of Ha'azinu, where Moshe Rabbeinu compares his teaching to rain, together with Yeshayahu's image that Hashem's word descends like rain and snow to do its work. Just as the earth cannot bring forth its strength without the rain and snow sent from Heaven, so a person cannot realize his potential without Heavenly assistance. That essential Heavenly help given to Bnei Yisrael is the Torah and the mitzvos, as hinted in Tehillim 147, which lists Hashem's gifts to nature and then crowns them with His relating His words to Yaakov. The heart of a Yisrael stays hard until the Torah, which is called water, softens and dissolves it, even when it is hard as stone. Moreover, the very word "yaarof" carries a connotation of killing, teaching that the Torah removes the "stiff neck" of the yetzer hara and ultimately slays it.