The Rambam relates that ultimately all the fast days will be transformed into festivals and days of celebration, implying that their inner message is positive. Indeed, as the Alter Rebbe mentions in Iggeres HaTeshuvah, a fast day is a “day of will (favourable time).” Moreover, this positive dimension is stronger on the Tenth of Teves than other fasts. Why so?
From the Rebbe’s explanations:
– Among the positive dimensions of fast days are that they are days of teshuvah. Teshuvah has the power to end the exile and bring the Redemption, for “Israel will be redeemed only through teshuvah.” “The Torah has promised that ultimately, Israel will turn [to G‑d] in teshuvah,… and immediately, she will be redeemed.”
We see this positive dimension in regard to the Tenth of Teves. For although it reflects a tragic event, the beginning of the siege of Jerusalem, nevertheless, at that time, Jerusalem, its walls, and surely, the Beis HaMikdash, remained untouched. The city remained intact.
What was the intent? That the Jews be aroused to teshuvah and had that happened, none of the subsequent tragedies would have occurred.
Thus on the Tenth of Teves, there is a greater emphasis on the concept that the entire purpose of the fast is to motivate the people to teshuvah.
Based on the Rebbe’s talk on Shabbos Parshas Vayechi and the Tenth of Teves, 5752.
The Beit haMikdash illustrations: The Temple Institute, Jerusalem.