3202 —פירוש י״ט כסלו כחג החגים

Regarding your note and question—the foundation and meaning of the title for the bright day of Yud Tes Kislev as "the festival of all festivals," as written in the introduction to the Yud Tes Kislev pamphlet: This introduction was written by my father-in-law, the Rebbe, of blessed memory, but for a certain reason he did not wish to sign it. The matter can be explained—even though I did not hear this from him—based on what is written in the book Me'ori Ori section 8, sub-section 5, which is based on what is found in Tikunei Zohar Tikkun 21 (70b), that 'the festival of all festivals' does not mean a separate festival per se, but rather refers to the central point revealed within all festivals (see also Be'er Lachai Ro'i and Biur HaGra).

The concept of festivals is joy (see Chagigah 10b: "but it comes..."), which connects you to G‑d. As our Sages ruled: there is no joy except with meat, specifically from the peace-offering of the festival—therefore nowadays there is only joy with wine (see also the precise wording of Rabbeinu HaZaken—the author of Tanya—in his Shulchan Aruch, Orach Chaim 529:7). This is one of the foundations of Chassidus, as emphasized in many places by the Baal Shem Tov and his disciples after him, and by Rabbeinu HaZaken and his disciples after him—the idea to serve G‑d with joy.

Another foundation: serving G‑d with one's body and not through fasts or self-mortification. As is well-known regarding the verse "When you see your enemy's donkey" (an instruction about the physical body's weightiness), "you shall surely help along with him"—specifically together with it (and not by rejecting it or through mortification).

The matter of Yud Tes Kislev—that our Rebbe was released below—is because permission was given from Above to spread Chassidus and its teachings. For no person stubs his toe etc.—meaning that Above they agreed specifically to spreading this approach. This is the central point within all festivals.

As with all such matters—in practice—there is also something new in Chassidus regarding Torah study: Chabad demands that everyone engage in learning the inner dimension of Torah in a way that he understands it with his own wisdom, understanding, and knowledge—even though there are hints in Torah that cannot yet be revealed or were revealed without being understood except through faith alone.

This is hinted at in Zohar III 93b onward and explained in Likkutei Torah (Tzav 11d) that this distinction exists between Shabbos—which is called Kodesh and in Zohar language "Kodesh milah b'garmei" (Zohar III 94b). Therefore Shabbos is called delight (oneg), not joy as above; it transcends comprehension and understanding—to such an extent that our Sages said they barely permitted speaking words of Torah on Shabbos (see end of Sha'ar HaYirah by Rabbeinu Yonah and additions to Torah Or at end of Parshas Ki Sisa). In contrast, Yom Tov is called Mikraei (and inviting/revealing) Kodesh, where work for food preparation is permitted.

In Chassidus language: like the difference between chochmah—which corresponds to Shabbos—whose essence lies in simple intellect received without debate or analysis; and binah—which corresponds to Yom Tov Mikraei Kodesh—comprehension and understanding. According to this too it becomes clear that Rabbeinu HaZaken's approach—to learn the inner dimension of Torah until one understands and grasps it—is indeed the central point among all festivals.

Summary

Yud Tes Kislev stands as a unique festival because it reveals the essential inner point connecting all Jewish holidays—the joyful service of G‑d through understanding His teachings. The spreading and comprehension of Chassidus mark this day as a unifying source for spiritual celebration.