(2) He prayed to the Eternal, saying, “O Eternal One! Isn’t this just what I said when I was still in my own country? That is why I fled beforehand to Tarshish. For I know that You are a compassionate and gracious God, slow to anger, abounding in kindness, renouncing punishment. (3) Please, Eternal One, take my life, for I would rather die than live.”
There were these hooligans in Rabbi Meir’s neighborhood who caused him a great deal of anguish. Rabbi Meir prayed for God to have mercy on them, that they should die. Rabbi Meir’s wife, B'ruria, said to him: What is your thinking? As it is written: “Let sins cease from the land” (Psalms 104:35). Is it written, "sinners?” "Sins" is written! Moreover, go to the end of the verse, “And the wicked will be no more.” Transgressions shall cease, and the wicked will be no more?! Rather, pray for God to have mercy on them, that they should repent. And he prayed for mercy on them, and they repented.
התשובה היא התופסת החלק היותר גדול בתורה ובחיים, עליה בנויות כל התקוות האישיות והצבוריות, היא המצות ה׳ שהיא מצד אחד קלה שבקלות, שהרי הרהור תשובה הוא כבר תשובה, ומצד אחד היא קשה שבקשות, שלא יצאה עדיין אל הפועל במלואה בעולם ובחיים.
From "Introduction of the Light of Teshuvah," Rav Avraham Yitzchak Kook.
Teshuvah is that which occupies the greater portion of the Torah and of life, upon it are built all of the hopes, both personal and public, and it is the commandment of God that, on the one hand of the simplest of simples one, for merely thinking about teshuvah is already teshuvah, and on the other hand it is the most difficult of difficult ones, for it never reaches its fullness or full potential in the world or in life.
And Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: All of the prophets only prophesied with regard to penitents but with regard to the full-fledged righteous “No eye has seen it, God, aside from You.” And this disagrees with Rabbi Abbahu, as Rabbi Abbahu said: In the place where penitents stand, even the full-fledged righteous do not stand, as it is stated: “Peace, peace upon the one who is far and the one who is near.” The one who is far (i.e. the penitent) and after peace is extended to the one who is near (i.e. the full-fledged righteous).
(א) אֵי זוֹ הִיא תְּשׁוּבָה גְּמוּרָה. זֶה שֶׁבָּא לְיָדוֹ דָּבָר שֶׁעָבַר בּוֹ וְאֶפְשָׁר בְּיָדוֹ לַעֲשׂוֹתוֹ וּפֵרַשׁ וְלֹא עָשָׂה מִפְּנֵי הַתְּשׁוּבָה. לֹא מִיִּרְאָה וְלֹא מִכִּשְׁלוֹן כֹּחַ. כֵּיצַד.
(1) What is complete teshuvah? The one who once more had in it in their power to repeat a violation, but separated themself therefrom, and did not do it because of teshuvah, and not out of fear or lack of strength.
Do not say that no teshuvah is needed except for sins to which action is attached, for example: prostitution, robbery, or theft. For even as it is necessary for people to turn away from such, so it is necessary for them to search their bad tendencies, to turn in teshuvah from anger, from hatred, from jealousy, from deceit, from pursuing after wealth, honor, feasting and such like these; from all of these it is necessary for one to turn in teshuvah. Indeed these iniquities are more grievous and more difficult for a person to be separated from than those which require action, for on such the prophet Isaiah said: "Let the wicked forsake their way, and the person of iniquity their thoughts" (Is. 55.7).
(ג) בפרשת התשובה כי המצוה הזאת כו'. כי הנה עיקר התשובה אינו על עבירה דווקא אך שצריך האדם לשוב להתדבק בשורשו. וע"ז אמרו חז"ל שמגעת עד כה"כ כלומר שצריכין לשוב אל החלק שיש לכל איש נשמת אלקי ממעל כמ"ש עד ה' אלקיך...ולכן כשאדם רואה שהוא רחוק מזה הדביקות כמ"ש ז"ל ואם רק נפלאת היא ממך צריכין ע"ז לשוב בתשובה. וזה הנתינת טעם על התשובה שידע האדם כי המצוה הזאת לא נפלאת כו' ולכן צריכין לשוב לזה הדביקות כנ"ל:
In the section of the Torah about teshuvah, the essence of teshuvah is not specifically about transgression, but that a human needs to do teshuvah, to cling to their Roots. About this the Rabbis say that [such a person] reaches the Throne of Glory, meaning that people need to return to the portion of the supernal divine soul that everyone has, as it is written: "to Hashem Your God."...When a human sees that they are far from this, as the Rabbis say, "But if it is only wondrous for you, for this reason one must do teshuvah." This is the basis for teshuvah: that a human knows that this commandment is not too wondrous...and thus one needs to do teshuvah, to cling to God, as was mentioned above.
היינו שאמר לו כי לא ניתן זמן לאדם לשוב להש"י רק בעודנו בחיים ואז אינו נקבע החטא ויוכל לשוב. אבל לפתח היינו כשאפס כח חיות האדם, אז החטא רובץ ולא יוכל לקום...
Mei Shiloach, Breisheet #13.
It is always time for a person to return to God while they are alive, and thus the sin is not fixed, and they have the ability to return. But "at the opening/door" refers to when a person's life-force is at zero, then sin crouches, and one cannot get up...
וַאֲפִלּוּ מִי שֶׁהוּא, חַס וְשָׁלוֹם, בַּמַּדְרֵגָה הַתַּחְתּוֹנָה לְגַמְרֵי, חַס וְשָׁלוֹם, רַחֲמָנָא לִצְלָן, אֲפִלּוּ אִם מֻנָּח בִּשְׁאוֹל תַּחְתִּיּוֹת, רַחֲמָנָא לִצְלָן, אַף־עַל־פִּי־כֵן אַל יִתְיָאֵשׁ עַצְמוֹ, וִיקַיֵּם: מִבֶּטֶן שְׁאוֹל שִׁוַּעְתִּי (יונה ב), וְיַחֲזִיק עַצְמוֹ בַּמֶּה שֶׁיּוּכַל, כִּי גַּם הוּא יָכוֹל לַחֲזֹר וְלָשׁוּב וּלְקַבֵּל חִיּוּת מֵהַתּוֹרָה עַל־יְדֵי הַצַּדִּיק הַנַּ"ל. וְהָעִקָּר – לְחַזֵּק עַצְמוֹ בְּכָל מַה שֶּׁאֶפְשָׁר, [כִּי אֵין שׁוּם יֵאוּשׁ בָּעוֹלָם כְּלָל. (וְאָמַר אָז בְּזֶה הַלָּשׁוֹן: קַיין יִאוּשׁ אִיז גָאר נִיט פַאר הַאנְדִין)...
And even someone who is in the lowest of low places, even if they are in the lowest rung of Sheol, even then they should not despair, and fulfill the verse: "From the belly of Sheol I cried to you" (Jonah 2), and they should strengthen themselves as much as they can, for one can return and do teshuvah and receive the life-force from the Torah by means of the righteous one. And the essence is to strengthen one's self as much as is possible because there is no despair in the world [Ein shum ye'ush ba'olam ]at all. As we say in Yiddish: Kein ye'ush iz gor nit far handen.