The Torah says (Bamidbar 10:10) שמחתכם וביום, "The day of your happiness", and Chazal say that this alludes to Yom Kippur. This is because Yom Kippur is a very happy day, the day our aveiros are removed from us. The kohen gadol is alone in Ohel Moed when he does the avodah, as it states (Vayikra 16:17) עַד ׁבַּק ֹּדֶש לְכַפ ֵּר בְּבֹאוֹ מוֹעֵד בְּאֹהֶל יִה ְיֶה לֹא אָדָם וְכָל יִשְׂרָאֵל קְהַל כָּל וּבְעַד בֵּיתוֹ וּבְעַד בַּע ֲדוֹ וְכִפ ֶּר צֵאתוֹ, "Any person shall not be in Ohel Moed when [Kohen Gadol] comes to provide atonement in the Midkash until his departure. He shall provide atonement for himself, for his household, and for the entire congregation of Yisrael." The roshei teivos of the words בַּע ֲדוֹ וְכִפ ֶּר צֵאתוֹ עַד ׁבַּק ֹּדֶש לְכַפ ֵּר בְּבֹאוֹ, spells עצוב בלב, with a sad heart. The pasuk hints that we don't enter the holiness of Yom Kippur with sadness. We should be happy on this day.
Meor Einayim (Haazinu) writes that teshuvah is a mitzvas asei, and therefore, it should be performed with simchah.
The Zohar says that there are aveiros that one can't do teshuvah on. This is because these aveiros bring a person to atzvus, and it is impossible to do teshuvah with sadness. However, when one strengthens himself and he does teshuvah with simchah, even those severe aveiros will be forgiven.
The Beis Aharon (p.131b) writes (regarding Rosh Hashanah), "Only with teshuvah and with yishuv hadaas, because simcha purifies the mind, and the primary teshuvah is with a pure mind."
The Chasam Sofer zt'l asks, it is known that when we do teshuvah, Moshiach will come. But why should our teshuvah bring Moshiach? Hashem does everything, and even our teshuvah is from Him. Hashem places the desire to do teshuvah into our hearts and helps us in every step of the process. So, why do we deserve salvation? Why should we deserve Mashiach if we are not the ones who do the teshuvah?
The Chasam Sofer answers this question by saying that our part of the teshuvah process is that we are happy with the teshuvah.
Chazal revealed (end of Taanis) that Yom Kippur is one of the happiest days of the year because on Yom Kippur, we become cleansed from all our sins. We deserve credit for being happy with our atonement. One could theoretically be upset about doing teshuvah because teshuvah means obedience to halachah and being restricted by the Torah's rules. But we want to do teshuvah and are happy that we are improving our ways. And for that, we deserve a reward.
It states (Tehillim 14:7), ישראל ישועת מציון יתן מי ישראל ישמח יעקב יגל עמו שבות 'ה בשוב. The Chasam Sofer explains that Dovid HaMelech asked ישראל ישועות מציון יתן מי, why do we deserve yeshuos? Although we do teshuvah, behold, עמו שבות 'ה בשוב, it is Hashem who is guiding us on the path of teshuvah. We aren't doing anything!
The answer is ישראל ישמח יעקב יגל. We are happy that Hashem is leading us on the path of teshuvah. For that, we deserve yeshuos and the upcoming redemption.
26. It states (Shir HaShirim 6:3) לי ודודי לדודי אני, "I am my beloved's, and my beloved is mine." The תיבות סופי, the final letters of these words are four ד"יוs, which is gematria 40. Reb Chaim Vital (תצא כי ,טוב הדעת עץ) teaches that this alludes to the forty days of Elul until Yom Kippur. Also, the roshei teivos of (Tehillim 53:7) ישמח יעקב יגל ישראל, "Yaakov will rejoice, Yisrael will be glad," are gematria 40. This hints that teshuvah of these days should be performed with simcha.
But how can one be happy if he is aware of his aveiros and knows how far he is from where he should be? The answer is that it states (Tehillim 105:3) 'ה מבקשי לב ישמח, "The heart of those who seek Hashem rejoice." It doesn't state 'ה רצון עושי לב ישמח, that the joy is for performing Hashem's will, rather, for desiring and striving to do Hashem's will. Everyone can reach that level.
