Halacha

הלכה א
הוֹאִיל וּרְשׁוּת כָּל אָדָם נְתוּנָה לוֹ כְּמוֹ שֶׁבֵּאַרְנוּ יִשְׁתַּדֵּל אָדָם לַעֲשׂוֹת תְּשׁוּבָה וּלְהִתְוַדּוֹת בְּפִיו מֵחֲטָאָיו וְלִנְעֹר כַּפָּיו מֵחֲטָאָיו כְּדֵי שֶׁיָּמוּת וְהוּא בַּעַל תְּשׁוּבָה וְיִזְכֶּה לְחַיֵּי הָעוֹלָם הַבָּא:
כסף משנה
1.
Since free choice is granted to all men as explained, a person should always strive to do Teshuvah and to confess verbally for his sins, striving to cleanse his hands from sin in order that he may die as a Baal-Teshuvah and merit the life of the world to come.

הלכה ב
לְעוֹלָם יִרְאֶה אָדָם עַצְמוֹ כְּאִלּוּ הוּא נוֹטֶה לָמוּת וְשֶׁמָּא יָמוּת בִּשְׁעָתוֹ וְנִמְצָא עוֹמֵד בְּחֶטְאוֹ. לְפִיכָךְ יָשׁוּב מֵחֲטָאָיו מִיָּד וְלֹא יֵאָמֵר כְּשֶׁאַזְקִין אָשׁוּב שֶׁמָּא יָמוּת טֶרֶם שֶׁיַּזְקִין. הוּא שֶׁשְּׁלֹמֹה אָמַר בְּחָכְמָתוֹ (קהלת ט ח) "בְּכָל עֵת יִהְיוּ בְגָדֶיךָ לְבָנִים":
כסף משנה
2.
A person should always view himself as leaning towards death, with the possibility that he might die at any time. Thus, he may be found as a sinner.
Therefore, one should always repent from his sins immediately and should not say: "When I grow older, I will repent," for perhaps he will die before he grows older. This was implied by the wise counsel given by Solomon [Ecclesiastes 9:8]: "At all times, your clothes should be white."

הלכה ג
אַל תֹּאמַר שֶׁאֵין תְּשׁוּבָה אֶלָּא מֵעֲבֵרוֹת שֶׁיֵּשׁ בָּהֶן מַעֲשֶׂה כְּגוֹן זְנוּת וְגֵזֶל וּגְנֵבָה. אֶלָּא כְּשֵׁם שֶׁצָּרִיךְ אָדָם לָשׁוּב מֵאֵלּוּ כָּךְ הוּא צָרִיךְ לְחַפֵּשׂ בְּדֵעוֹת רָעוֹת שֶׁיֵּשׁ לוֹ וְלָשׁוּב מִן הַכַּעַס וּמִן הָאֵיבָה וּמִן הַקִּנְאָה וּמִן הַהִתּוּל וּמֵרְדִיפַת הַמָּמוֹן וְהַכָּבוֹד וּמֵרְדִיפַת הַמַּאֲכָלוֹת וְכַיּוֹצֵא בָּהֶן מִן הַכּל צָרִיךְ לַחֲזֹר בִּתְשׁוּבָה. וְאֵלּוּ הָעֲוֹנוֹת קָשִׁים מֵאוֹתָן שֶׁיֵּשׁ בָּהֶן מַעֲשֶׂה שֶׁבִּזְמַן שֶׁאָדָם נִשְׁקָע בְּאֵלּוּ קָשֶׁה הוּא לִפְרשׁ מֵהֶם. וְכֵן הוּא אוֹמֵר (ישעיה נה ז) "יַעֲזֹב רָשָׁע" וְגוֹ':
כסף משנה
3.
A person should not think that repentance is only necessary for those sins that involve deed such as promiscuity, robbery, or theft. Rather, just as a person is obligated to repent from these, similarly, he must search after the evil character traits he has. He must repent from anger, hatred, envy, frivolity, the pursuit of money and honor, the pursuit of gluttony, and the like. He must repent for all [of the above].
These sins are more difficult than those that involve deed. If a person is attached to these, it is more difficult for him to separate himself. In this context, [Isaiah 55:7] exhorts: "May the wicked abandon his path and the crooked man, his designs."

הלכה ד
וְאַל יְדַמֶּה אָדָם בַּעַל תְּשׁוּבָה שֶׁהוּא מְרֻחָק מִמַּעֲלַת הַצַּדִּיקִים מִפְּנֵי הָעֲוֹנוֹת וְהַחֲטָאוֹת שֶׁעָשָׂה. אֵין הַדָּבָר כֵּן אֶלָּא אָהוּב וְנֶחְמָד הוּא לִפְנֵי הַבּוֹרֵא כְּאִלּוּ לֹא חָטָא מֵעוֹלָם. וְלֹא עוֹד אֶלָּא שֶׁשְּׂכָרוֹ הַרְבֵּה שֶׁהֲרֵי טָעַם טַעַם הַחֵטְא וּפֵרַשׁ מִמֶּנּוּ וְכָבַשׁ יִצְרוֹ. אָמְרוּ חֲכָמִים מָקוֹם שֶׁבַּעֲלֵי תְּשׁוּבָה עוֹמְדִין אֵין צַדִּיקִים גְּמוּרִין יְכוֹלִין לַעֲמֹד בּוֹ. כְּלוֹמַר מַעֲלָתָן גְּדוֹלָה מִמַּעֲלַת אֵלּוּ שֶׁלֹּא חָטְאוּ מֵעוֹלָם מִפְּנֵי שֶׁהֵן כּוֹבְשִׁים יִצְרָם יוֹתֵר מֵהֶם:
כסף משנה
4.
A Baal-Teshuvah should not consider himself distant from the level of the righteous because of the sins and transgressions that he committed. This is not true. He is beloved and desirable before the Creator as if he never sinned.
Furthermore, he has a great reward for he has tasted sin and yet, separated himself from it, conquering his [evil] inclination. Our Sages declared: "In the place where Baalei Teshuvah stand, even the completely righteous are not able to stand." The level of Baalei Teshuvah transcends the level of those who never sinned at all, for they overcome their [evil] inclination more.

הלכה ה
כָּל הַנְּבִיאִים כֻּלָּן צִוּוּ עַל הַתְּשׁוּבָה וְאֵין יִשְׂרָאֵל נִגְאָלִין אֶלָּא בִּתְשׁוּבָה. וּכְבָר הִבְטִיחָה תּוֹרָה שֶׁסּוֹף יִשְׂרָאֵל לַעֲשׂוֹת תְּשׁוּבָה בְּסוֹף גָּלוּתָן וּמִיָּד הֵן נִגְאָלִין שֶׁנֶּאֱמַר (דברים ל א) "וְהָיָה כִי יָבֹאוּ עָלֶיךָ כָּל הַדְּבָרִים" וְגוֹ' (דברים ל ב) "וְשַׁבְתָּ עַד ה' אֱלֹהֶיךָ" (דברים ל ג) "וְשָׁב ה' אֱלֹהֶיךָ" וְגוֹ':
כסף משנה
5.
All the prophets commanded [the people] to repent. Israel will only be redeemed through Teshuvah.
The Torah has already promised that, ultimately, Israel will repent towards the end of her exile and, immediately, she will be redeemed as [Deuteronomy 30:1-3] states: ”There shall come a time when [you will experience] all these things... and you will return to God, your Lord.... God, your Lord, will bring back your [captivity].”

הלכה ו
גְּדוֹלָה תְּשׁוּבָה שֶׁמְּקָרֶבֶת אֶת הָאָדָם לַשְּׁכִינָה שֶׁנֶּאֱמַר (הושע יד ב) "שׁוּבָה יִשְׂרָאֵל עַד ה' אֱלֹהֶיךָ". וְנֶאֱמַר (עמוס ד ו) "וְלֹא שַׁבְתֶּם עָדַי נְאֻם ה'. "וְנֶאֱמַר (ירמיה ד א) "אִם תָּשׁוּב יִשְׂרָאֵל נְאֻם ה' אֵלַי תָּשׁוּב". כְּלוֹמַר אִם תַּחֲזֹר בִּתְשׁוּבָה בִּי תִּדְבַּק. הַתְּשׁוּבָה מְקָרֶבֶת אֶת הָרְחוֹקִים. אֶמֶשׁ הָיָה זֶה שָׂנאוּי לִפְנֵי הַמָּקוֹם מְשֻׁקָּץ וּמְרֻחָק וְתוֹעֵבָה. וְהַיּוֹם הוּא אָהוּב וְנֶחְמָד קָרוֹב וְיָדִיד. וְכֵן אַתָּה מוֹצֵא שֶׁבְּלָשׁוֹן שֶׁהַקָּדוֹשׁ בָּרוּךְ הוּא מַרְחִיק הַחוֹטְאִים בָּהּ מְקָרֵב אֶת הַשָּׁבִים בֵּין יָחִיד בֵּין רַבִּים. שֶׁנֶּאֱמַר (הושע ב א) "וְהָיָה בִּמְקוֹם אֲשֶׁר יֵאָמֵר לָהֶם לֹא עַמִּי אַתֶּם יֵאָמֵר לָהֶם בְּנֵי אֵל חָי". וְנֶאֱמַר בִּיכָנְיָהוּ בְּרִשְׁעָתוֹ (כְּתֹב) [כִּתְבוּ] (ירמיה כב ל) "אֶת הָאִישׁ הַזֶּה עֲרִירִי גֶּבֶר לֹא יִצְלַח בְּיָמָיו", (ירמיה כב כד) "אִם יִהְיֶה כָּנְיָהוּ בֶּן יְהוֹיָקִים מֶלֶךְ יְהוּדָה חוֹתָם עַל יַד יְמִינִי" וְגוֹ'. וְכֵיוָן שֶׁשָּׁב בְּגָלוּתוֹ נֶאֱמַר בִּזְרֻבָּבֶל בְּנוֹ (חגי ב כג) "בַּיּוֹם הַהוּא נְאֻם ה' צְבָאוֹת אֶקָּחֲךָ זְרֻבָּבֶל בֶּן שְׁאַלְתִּיאֵל עַבְדִּי נְאֻם ה' וְשַׂמְתִּיךָ כַּחוֹתָם":
כסף משנה
6.
Teshuvah is great for it draws a man close to the Shechinah as [Hoshea 14:2] states: "Return, O Israel, to God, your Lord;" [Amos 4:6] states: "`You have not returned to Me,' declares God;" and [Jeremiah 4:1] states: "`If, you will return, O Israel,' declares God, `You will return to Me.'" Implied is that if you will return in Teshuvah, you will cling to Me.
Teshuvah brings near those who were far removed. Previously, this person was hated by God, disgusting, far removed, and abominable. Now, he is beloved and desirable, close, and dear.
Similarly, we find God employs the same expression with which He separates [Himself] from the sinners to draw close those who repent. [Hoshea 2:1] states: "Instead of saying to you: `You are not My nation,' He will tell you: `You are the children of the living God.'”
[Also, Jeremiah] speaks of Yecheniah while he was wicked [with the expression (22:30)]: "Write down this man as childless, a man who shall never prosper in his days," and [22:24]: "Would Cheniah, the son of Yehoyakim, king of Judah, be the signet ring on My right hand, I would tear him off." However, after he repented when in exile, [Chaggai 2:23] said concerning Zerubavel, his son: "'On that day,' declares the God of Hosts, `I will take you, Zerubavel, the son of Shaltiel, My servant,' declares God, `and I will place you as a signet ring.'"

הלכה ז
כַּמָּה מְעֻלָּה מַעֲלַת הַתְּשׁוּבָה. אֶמֶשׁ הָיָה זֶה מֻבְדָּל מֵה' אֱלֹהֵי יִשְׂרָאֵל שֶׁנֶּאֱמַר (ישעיה נט ב) "עֲוֹנוֹתֵיכֶם הָיוּ מַבְדִּלִים בֵּינֵכֶם לְבֵין אֱלֹהֵיכֶם". צוֹעֵק וְאֵינוֹ נַעֲנֶה שֶׁנֶּאֱמַר (ישעיה א טו) "כִּי תַרְבּוּ תְפִלָּה" וְגוֹ'. וְעוֹשֶׂה מִצְוֹת וְטוֹרְפִין אוֹתָן בְּפָנָיו שֶׁנֶּאֱמַר (ישעיה א יב) "מִי בִקֵּשׁ זֹאת מִיֶּדְכֶם רְמֹס חֲצֵרָי", (מלאכי א י) "מִי גַם בָּכֶם וְיִסְגֹּר דְּלָתַיִם" וְגוֹ'. וְהַיּוֹם הוּא מֻדְבָּק בַּשְּׁכִינָה שֶׁנֶּאֱמַר (דברים ד ד) "וְאַתֶּם הַדְּבֵקִים בַּה' אֱלֹהֵיכֶם". צוֹעֵק וְנַעֲנֶה מִיָּד שֶׁנֶּאֱמַר (ישעיה סה כד) "וְהָיָה טֶרֶם יִקְרָאוּ וַאֲנִי אֶעֱנֶה". וְעוֹשֶׂה מִצְוֹת וּמְקַבְּלִין אוֹתָן בְּנַחַת וְשִׂמְחָה שֶׁנֶּאֱמַר (קהלת ט ז) "כִּי כְבָר רָצָה הָאֱלֹהִים אֶת מַעֲשֶׂיךָ". וְלֹא עוֹד אֶלָּא שֶׁמִּתְאַוִּים לָהֶם שֶׁנֶּאֱמַר (מלאכי ג ד) "וְעָרְבָה לַה' מִנְחַת יְהוּדָה וִירוּשָׁלםִ כִּימֵי עוֹלָם וּכְשָׁנִים קַדְמֹנִיּוֹת":
כסף משנה
7.
How exalted is the level of Teshuvah! Previously, the [transgressor] was separate from God, the Lord of Israel, as [Isaiah 59:2] states: "Your sins separate between you and your God." He would call out [to God] without being answered as [Isaiah 1:15] states: "Even if you pray many times, I will not hear."
He would fulfill mitzvot, only to have them crushed before him as [Isaiah 1:12] states: "Who asked this from you, to trample in My courts," and [Malachi 1:10] states: "`O were there one among you who would shut the doors that you might not kindle fire on My altar for no reason! I have no pleasure in you,' says the God of Hosts, `nor will I accept an offering from your hand.'”
Now, he is clinging to the Shechinah as [Deuteronomy 4:4] states: "And you who cling to God, your Lord." He calls out [to God] and is answered immediately as [Isaiah 65:24] states: "Before, you will call out, I will answer." He fulfills mitzvot and they are accepted with pleasure and joy as [Ecclesiastes 9:7] states, "God has already accepted your works," moreover, [G‑d] desires them, as [Malachi 3:4] states: "Then, shall the offering of Judah and Jerusalem be pleasing to God as in days of old and as in the former years."

הלכה ח
בַּעֲלֵי תְּשׁוּבָה דַּרְכָּן לִהְיוֹת שְׁפָלִים וַעֲנָוִים בְּיוֹתֵר. אִם חֵרְפוּ אוֹתָן הַכְּסִילִים בְּמַעֲשֵׂיהֶם הָרִאשׁוֹנִים וְאָמְרוּ לָהֶן אֶמֶשׁ הָיִיתָ עוֹשֶׂה כָּךְ וְכָךְ וְאֶמֶשׁ הָיִיתָ אוֹמֵר כָּךְ וְכָךְ. אַל יַרְגִּישׁוּ לָהֶן אֶלָּא שׁוֹמְעִין וּשְׂמֵחִים וְיוֹדְעִין שֶׁזּוֹ זְכוּת לָהֶם. שֶׁכָּל זְמַן שֶׁהֵם בּוֹשִׁים מִמַּעֲשֵׂיהֶם שֶׁעָבְרוּ וְנִכְלָמִים מֵהֶן זְכוּתָם מְרֻבָּה וּמַעֲלָתָם מִתְגַּדֶּלֶת. וְחֵטְא גָּמוּר הוּא לוֹמַר לְבַעַל תְּשׁוּבָה זְכֹר מַעֲשֶׂיךָ הָרִאשׁוֹנִים אוֹ לְהַזְכִּירָן לְפָנָיו כְּדֵי לְבַיְּשׁוֹ. אוֹ לְהַזְכִּיר דְּבָרִים וְעִנְיָנִים הַדּוֹמִין לָהֶם כְּדֵי לְהַזְכִּירוֹ מֶה עָשָׂה. הַכּל אָסוּר וּמֻזְהָר עָלָיו בִּכְלַל הוֹנָיַת דְּבָרִים שֶׁהִזְהִירָה תּוֹרָה עָלֶיהָ שֶׁנֶּאֱמַר (ויקרא כה יז) "וְלֹא תוֹנוּ אִישׁ אֶת עֲמִיתוֹ":
כסף משנה
8.
The manner of Baalei Teshuvah is to be very humble and modest.
If fools shame them because of their previous deeds, saying to them: "Yesterday, you would commit such and such [sins]. Yesterday, you would commit these and these [transgressions]," they will pay no attention to them. On the contrary, they will hear [this abuse] and rejoice, knowing that it is a merit for them.
Whenever they are embarrassed for the deeds they committed and shamed because of them, their merit increases and their level is raised.
It is a utter sin to tell a Baal Teshuvah, "Remember your previous deeds," or to recall them in his presence to embarrass him or to mention the surrounding circumstances or other similar matters so that he will recall what he did. This is all forbidden. We are warned against it within the general category of verbal abuse which Torah has warned us against as [Leviticus 25:17] states: "A man should not mistreat his colleague."

מדע הלכות תשובה פרק ז
Madda Teshuvah Chapter 7