Avodah Zarah 5A

לומר לך, שאם חטא יחיד ⁠— אומרים לו: כלך אצל יחיד, ואם חטאו צבור ⁠— אומרים לו: כלך אצל צבור.

This serves to say to you that if an individual has sinned, one says to him: Go to that famous individual who sinned, King David, and learn from him that one can repent. And if the community sinned, one says to them: Go to the community that sinned, i.e., the Jewish people at the time of the Golden Calf.

וצריכא, דאי אשמועינן יחיד ⁠— משום דלא מפרסם חטאיה, אבל צבור דמפרסם חטאיהו ⁠— אימא לא. ואי אשמועינן צבור ⁠— משום דנפישי רחמייהו, אבל יחיד דלא אלימא זכותיה ⁠— אימא לא, צריכא.

The Talmud notes: And it is necessary to learn about repentance both in the case of an individual and in the case of a community. The reason is that if we had learned this idea only with regard to an individual, one might have thought that he has the option to repent only because his sin is not publicized. But in the case of a community, whose sin is publicized, one might say that the community cannot repent. And likewise, if we had learned this idea only with regard to a community, one might have said that their repentance is accepted because their prayers are more numerous than those of an individual, and they are heard before God. But in the case of an individual, whose merit is not as strong, one might say that he is not able to repent. Therefore, it is necessary to teach both cases.

והיינו דרבי שמואל בר נחמני אמר רבי יונתן, מאי דכתיב ״נאם דוד בן ישי ונאם הגבר הקם על״? נאם דוד בן ישי שהקים עולה של תשובה.

And this is similar to that which R' Shmuel bar Naḥmani says that R' Yonatan says: What is the meaning of that which is written: “The saying of David, son of Yishai, and the saying of the man raised on high [al]” (II Samuel 23:1)? This is the meaning of the verse: The saying of David, son of Yishai, who raised and lightened the yoke [ullah] of repentance, as he taught the power of repentance through his own example.