Baalei teshuvah enter the innermost place

כתיב אשרי תבחר ותקרב ישכון חצריך.

It is written: "Fortunate is the one You choose and bring near, that he may dwell in Your courtyards." (Tehillim 65:5)

The pasuk praises the one whom Hashem both chooses and draws near to dwell in His courts.

ובמד' במדבר אשרי מי שבחרו אעפ"י שלא קירבו כו' אהרן בחרו וקירבו ע"ש.

And in the Midrash Bamidbar: "Fortunate is the one He chose, even if He did not bring him near... Aharon — He chose him and brought him near," see there.

The Midrash notes that being chosen alone is fortunate, but Aharon merited both being chosen and being brought near.

והיינו שנתקרב אהרן לכנוס לפני ולפנים ע"י שנתקיים בו בחרו וקירבו.

And this means that Aharon was brought near to enter the innermost chamber (lifnai ve-lifnim), because in him was fulfilled both "He chose him" and "He brought him near."

Because Aharon was both chosen and drawn close, he merited to enter the Holy of Holies.

וכמו כן בדוד המע"ה שהוא בעל תשובה איתא אין ישיבה בעזרה אלא למלכי בית דוד בלבד.

And likewise regarding David HaMelech, who is a baal teshuvah, it is taught that there is no sitting in the Azarah (Temple courtyard) except for the kings of the house of David alone. (Yoma 25a)

David, the archetypal baal teshuvah, was uniquely granted the right to sit in the Temple courtyard — a privilege denied to all others.

ועל הענין הזה אמרו במקום שבע"ת עומדין אין צדיקים גמורים יכולין לעמוד.

And concerning this matter they said: "In the place where baalei teshuvah stand, complete tzaddikim cannot stand." (Berachos 34b)

Those who return from sin reach a level even perfectly righteous tzaddikim cannot attain.

ואע"פ שמרע"ה הי' למעלה יותר ויותר.

And even though Moshe Rabbeinu was on a far, far higher level —

Although Moshe stood incomparably higher than Aharon —

אעפ"כ נבחר אהרן לכנוס לפני ולפנים כנ"ל.

— nevertheless Aharon was chosen to enter the innermost chamber, as above.

— it was specifically Aharon, not Moshe, who was chosen to enter the Holy of Holies.

ודבר זה מתקיים ג"כ בחג הסוכות שבנ"י המה בעלי תשובה זוכין להיות נכנסי' בסוכה שחל עלי' שם שמים כמ"ש חז"ל.

And this matter is fulfilled also on the festival of Sukkos, that Bnei Yisrael, who are baalei teshuvah [after Yom Kippur], merit to enter the sukkah, upon which rests the Name of Heaven, as Chazal said.

Having just done teshuvah on Yom Kippur, Bnei Yisrael enter the sukkah, a structure that bears Hashem's Name.

ולכך צריך להיות גבוה עשרה טפחים.

And therefore it must be at least ten handbreadths (tefachim) high.

The sukkah's minimum height of ten tefachim is itself significant.

משום דמעולם לא שרתה שכינה למטה מעשרה ע"ש פ"ק דסוכה.

Because the Shechinah never rested below ten [tefachim], see there in the first chapter of Sukkah. (Sukkah 5a)

Since the Divine Presence rests only above ten tefachim, the sukkah must reach that height to host the Shechinah.

והטעם נראה כי הקב"ה וב"ש מטיב לכל מי שיכול לקבל הטובה.

And the reason appears to be that Hashem, blessed is He, bestows good upon anyone who is able to receive the good.

Hashem grants His goodness to whoever is capable of properly receiving it.

וע"י שבע"ת לבו נכנע ביותר יכולין להכניסו לפנים שלא יבוא עי"ז לידי גיאות ח"ו.

And because the heart of the baal teshuvah is exceedingly humbled, he can be brought inside, so that he will not come to arrogance (gaivah), Heaven forbid, through this.

The baal teshuvah's deep humility makes it safe to bring him close, since he will not become proud from the elevation.

ולכך יכול בע"ת לעמוד במקום שצדיקים גמורים א"י לעמוד שם.

And therefore the baal teshuvah can stand in a place where complete tzaddikim cannot stand.

His humility is precisely what allows the baal teshuvah to occupy a level closed to flawless tzaddikim.

כי בע"כ יהי' להם גבהות יותר מבעלי תשובה:

For inevitably they [the complete tzaddikim] will have more loftiness/pride than the baalei teshuvah.

A flawless tzaddik is unavoidably more prone to a sense of elevation than one who has had to humble himself through teshuvah.

Summary: The greatest closeness to Hashem is reserved for those who are both "chosen and brought near" — like Aharon, who entered the Holy of Holies even over Moshe, and David, the baal teshuvah, who alone could sit in the Azarah. Because "in the place where baalei teshuvah stand, complete tzaddikim cannot stand," the deeply humbled heart of one who returns can be safely drawn inside without risk of arrogance. So too on Sukkos: Bnei Yisrael, freshly returned through teshuvah on Yom Kippur, enter the sukkah — built ten tefachim high so the Shechinah can rest upon them.