7 Tishrei 5780
Erev Shabbat Kodesh
Parashat Ha'azinu - Shabbat Shuvah
The Shabbat between Rosh Hashanah and Yom Kippur is called Shabbat Shuvah because its special haftarah reading begins with the words Shuvah Yisrael ["Return O Israel"] from the prophecy of Hoshe'a. It is also referred to as Shabbat Shuvah because it falls during the ten days of Teshuvah - Repentance.
...It is customary in almost all Jewish communities for the rabbi of the city or congregation to expound on teshuvah, and to emphasize the severity of transgression so that the people turn their hearts toward repentance. Our Sages have said that when the wise address the people, God forgives the sins of Israel.
...on Shabbat Shuvah one should be especially careful to concentrate entirely on Torah, prayer, and reflection on teshuvah, thereby attaining forgiveness for whatever unfitting behavior may have marred other Sabbaths.