The Talmud's central discussion of teshuva: Yom Kippur atones only for sins between man and God; sins between man and man require first making amends. It also discusses the greatness of a ba'al teshuvah, whose intentional sins are transformed into merits.
מַתְנִי׳ חַטָּאת וְאָשָׁם וַדַּאי — מְכַפְּרִין. מִיתָה וְיוֹם הַכִּפּוּרִים — מְכַפְּרִין עִם הַתְּשׁוּבָה. תְּשׁוּבָה — מְכַפֶּרֶת עַל עֲבֵירוֹת קַלּוֹת: עַל עֲשֵׂה, וְעַל לֹא תַעֲשֶׂה. וְעַל הַחֲמוּרוֹת הוּא תּוֹלֶה, עַד שֶׁיָּבֹא יוֹם הַכִּפּוּרִים וִיכַפֵּר. הָאוֹמֵר: אֶחֱטָא וְאָשׁוּב, אֶחֱטָא וְאָשׁוּב — אֵין מַסְפִּיקִין בְּיָדוֹ לַעֲשׂוֹת תְּשׁוּבָה. אֶחֱטָא וְיוֹם הַכִּפּוּרִים מְכַפֵּר — אֵין יוֹם הַכִּפּוּרִים מְכַפֵּר. עֲבֵירוֹת שֶׁבֵּין אָדָם לַמָּקוֹם — יוֹם הַכִּפּוּרִים מְכַפֵּר, עֲבֵירוֹת שֶׁבֵּין אָדָם לַחֲבֵירוֹ — אֵין יוֹם הַכִּפּוּרִים מְכַפֵּר, עַד שֶׁיְּרַצֶּה אֶת חֲבֵירוֹ. דָּרַשׁ רַבִּי אֶלְעָזָר בֶּן עֲזַרְיָה: ״מִכֹּל חַטֹּאתֵיכֶם לִפְנֵי ה׳ תִּטְהָרוּ״. עֲבֵירוֹת שֶׁבֵּין אָדָם לַמָּקוֹם — יוֹם הַכִּפּוּרִים מְכַפֵּר. עֲבֵירוֹת שֶׁבֵּין אָדָם לַחֲבֵירוֹ — אֵין יוֹם הַכִּפּוּרִים מְכַפֵּר עַד שֶׁיְּרַצֶּה אֶת חֲבֵירוֹ. אָמַר רַבִּי עֲקִיבָא: אַשְׁרֵיכֶם יִשְׂרָאֵל! לִפְנֵי מִי אַתֶּם מִטַּהֲרִין, מִי מְטַהֵר אֶתְכֶם? אֲבִיכֶם שֶׁבַּשָּׁמַיִם, שֶׁנֶּאֱמַר: ״וְזָרַקְתִּי עֲלֵיכֶם מַיִם טְהוֹרִים וּטְהַרְתֶּם״, וְאוֹמֵר: ״מִקְוֵה יִשְׂרָאֵל (ה׳)״, מָה מִקְוֶה מְטַהֵר אֶת הַטְּמֵאִים — אַף הַקָּדוֹשׁ בָּרוּךְ הוּא מְטַהֵר אֶת יִשְׂרָאֵל. עָבַר עַל עֲשֵׂה וְשָׁב — אֵינוֹ זָז מִשָּׁם עַד שֶׁמּוֹחֲלִין לוֹ, שֶׁנֶּאֱמַר: ״שׁוּבוּ בָּנִים שׁוֹבָבִים״. עָבַר עַל לֹא תַעֲשֶׂה וְעָשָׂה תְּשׁוּבָה — תְּשׁוּבָה תּוֹלָה, וְיוֹם הַכִּפּוּרִים מְכַפֵּר. שֶׁנֶּאֱמַר: ״כִּי בַיּוֹם הַזֶּה יְכַפֵּר עֲלֵיכֶם מִכֹּל חַטֹּאתֵיכֶם״. עָבַר עַל כָּרֵיתוֹת וּמִיתוֹת בֵּית דִּין וְעָשָׂה תְּשׁוּבָה — תְּשׁוּבָה וְיוֹם הַכִּפּוּרִים תּוֹלִין, וְיִסּוּרִין מְמָרְקִין. שֶׁנֶּאֱמַר: ״וּפָקַדְתִּי בְשֵׁבֶט פִּשְׁעָם וּבִנְגָעִים עֲוֹנָם״. אֲבָל מִי שֶׁיֵּשׁ חִילּוּל הַשֵּׁם בְּיָדוֹ — אֵין לוֹ כֹּחַ בִּתְשׁוּבָה לִתְלוֹת וְלֹא בְּיוֹם הַכִּפּוּרִים לְכַפֵּר וְלֹא בְּיִסּוּרִין לְמָרֵק, אֶלָּא כּוּלָּן תּוֹלִין, וּמִיתָה מְמָרֶקֶת, שֶׁנֶּאֱמַר: ״וְנִגְלָה בְאׇזְנָי ה׳ צְבָאוֹת אִם יְכוּפַּר הֶעָוֹן הַזֶּה לָכֶם עַד תְּמוּתוּן״. אָמַר רַבִּי חָמָא (בַּר) חֲנִינָא: גְּדוֹלָה תְּשׁוּבָה שֶׁמְּבִיאָה רִפְאוּת לְעוֹלָם, שֶׁנֶּאֱמַר: ״אֶרְפָּא מְשׁוּבָתָם אוֹהֲבֵם נְדָבָה״. רַבִּי חָמָא (בַּר) חֲנִינָא רָמֵי, כְּתִיב: ״שׁוּבוּ בָּנִים שׁוֹבָבִים״, דְּמֵעִיקָּרָא שׁוֹבָבִים אַתֶּם, וּכְתִיב: ״אֶרְפָּא מְשׁוּבוֹתֵיכֶם״! לָא קַשְׁיָא: כָּאן מֵאַהֲבָה, כָּאן מִיִּרְאָה.
MISHNA: A sin-offering, which atones for unwitting performance of transgressions punishable by karet, and a definite guilt-offering, which is brought for robbery and misuse of consecrated items, atone for those sins. Death and Yom Kippur atone for sins when accompanied by repentance. Repentance itself atones for minor transgressions, for both positive mitzvot and negative mitzvot. And repentance places punishment for severe transgressions in abeyance until Yom Kippur comes and completely atones for the transgression. With regard to one who says: I will sin and then I will repent, I will sin and I will repent, Heaven does not provide him the opportunity to repent, and he will remain a sinner all his days. With regard to one who says: I will sin and Yom Kippur will atone for my sins, Yom Kippur does not atone for his sins. Furthermore, for transgressions between a person and God, Yom Kippur atones; however, for transgressions between a person and another, Yom Kippur does not atone until he appeases the other person. Similarly, Rabbi Elazar ben Azarya taught that point from the verse: “From all your sins you shall be cleansed before the Lord” (Leviticus 16:30). For transgressions between a person and God, Yom Kippur atones; however, for transgressions between a person and another, Yom Kippur does not atone until he appeases the other person. In conclusion, Rabbi Akiva said: How fortunate are you, Israel; before Whom are you purified, and Who purifies you? It is your Father in Heaven, as it is stated: “And I will sprinkle purifying water upon you, and you shall be purified” (Ezekiel 36:25). And it says: “The ritual bath of Israel is God” (Jeremiah 17:13). Just as a ritual bath purifies the impure, so too, the Holy One, Blessed be He, purifies Israel. These are the categories: If one violates a positive mitzva and repents, he is forgiven even before he moves from his place, i.e. immediately, as it is stated: “Return, you backsliding children, I will heal your backsliding” (Jeremiah 3:22), implying that when one repents he is immediately forgiven. If one violates a prohibition and repents, repentance suspends his punishment and Yom Kippur atones for his sin, as it is stated: “For on this day shall atonement be made for you, to purify you from all your sins” (Leviticus 16:30). If one commits a transgression that warrants karet or a sin punishable by death from the earthly court and then repents, repentance and Yom Kippur suspend his punishment, and suffering absolves and completes the atonement, as it is stated: “Then will I visit their transgression with the rod, and their iniquity with strokes” (Psalms 89:33). But in the case of one who has caused desecration of God’s name, his repentance has no power to suspend punishment, nor does Yom Kippur have power to atone for his sin, nor does suffering alone have power to absolve him. Rather, all these suspend punishment, and death absolves him, as it is stated: “And the Lord of Hosts revealed Himself to my ears: This iniquity shall not be atoned for until you die” (Isaiah 22:14). § Further on the topic of repentance, Rabbi Ḥama bar Ḥanina said: Great is repentance, as it brings healing to the world, as it is stated: “I will heal their backsliding, I will love them freely” (Hosea 14:5), which teaches that repentance from sin brings healing. Rabbi Ḥama bar Ḥanina raised a contradiction between two verses. It is written in one verse: “Return, you backsliding children” (Jeremiah 3:14), implying that initially when you sinned, it was only because you were backsliding, i.e., rebelling. It was merely an act of immaturity and foolishness and could be ignored as if it had never happened. But it is written: “I will heal your backsliding” (Jeremiah 3:22), implying that He will heal the sin from this point onward, and that they are still sinners. He resolved this contradiction, explaining that this is not difficult: Here, where everything is forgiven as if the Jewish people never sinned, it is referring to repentance out of love; there, where the sin is still remembered despite the forgiveness and repentance, it is referring to repentance out of fear.