תחת אשר לא עבדת כו' בשמחה
Because you did not serve Hashem your G-d with Simcha
The Torah seems to suggest that the punishments of the Tochecha will befall the Jewish people on account of a lack of Simcha - joy - in their service of Hashem.
Simcha is an integral element in serving Hashem, as stated by King David in Tehillim עבדו את ה ‘בשמחה בואו לפניו ברננה, “Serve Hashem with happiness, come before Him with joyful sound”.
We were created to serve Hashem and every moment of our lives is supposed to be lived for this pursuit. Since we are constantly in the service of Hashem and serving Hashem must be with Simcha, this means that we are always meant to be joyous.
Teshuvah is often associated with sadness or bitterness as we introspect and focus on our sins and shortcomings. But Teshuvah is part of serving Hashem. And so, even Teshuvah must be approached and performed with Simcha.
By meditating on the fact that no matter what we have done, Hashem gives us the opportunity to do Teshuvah - to make amends, to have another chance and to reconnect with Him, this itself should give us joy.
The Tzaddik Reb Simcha Bunem of Peshischa, explained that there is a connection between the month of Elul and Simcha. The above quoted verse has 2 parts. “Come before Him” refers to the Yomim Noraim, when we come before Hashem in prayer. Prior to that, we have to fulfill the beginning of the Posuk, “serve Hashem with happiness”. This refers to the month of Elul.
We start Selichos on Motzai Shabbos to enter the Selichos prayers with the Simcha of Shabbos. Avodah without Simcha brings curses. With Simcha, we will merit the ultimate blessings.
