Halacha

הלכה א
אַרְבָעָה וְעֶשְׂרִים דְּבָרִים מְעַכְּבִין אֶת הַתְּשׁוּבָה. אַרְבָּעָה מֵהֶן עָוֹן גָּדוֹל וְהָעוֹשֶׂה אֶחָד מֵהֶן אֵין הַקָּדוֹשׁ בָּרוּךְ הוּא מַסְפִּיק בְּיָדוֹ לַעֲשׂוֹת תְּשׁוּבָה לְפִי גֹּדֶל חֶטְאוֹ. וְאֵלּוּ הֵן. א) הַמַּחְטִיא אֶת הָרַבִּים וּבִכְלַל עָוֹן זֶה הַמְעַכֵּב אֶת הָרַבִּים מִלַּעֲשׂוֹת מִצְוָה. ב) וְהַמַּטֶּה אֶת חֲבֵרוֹ מִדֶּרֶךְ טוֹבָה לְרָעָה כְּגוֹן מֵסִית וּמַדִּיחַ. ג) הָרוֹאֶה בְּנוֹ יוֹצֵא לְתַרְבּוּת רָעָה וְאֵינוֹ מְמַחֶה בְּיָדוֹ. הוֹאִיל וּבְנוֹ בִּרְשׁוּתוֹ אִלּוּ מִחָה בּוֹ הָיָה פּוֹרֵשׁ וְנִמְצָא כְּמַחְטִיאוֹ. וּבִכְלַל עָוֹן זֶה כָּל שֶׁאֶפְשָׁר בְּיָדוֹ לִמְחוֹת בַּאֲחֵרִים בֵּין יָחִיד בֵּין רַבִּים וְלֹא מִחָה אֶלָּא יַנִּיחֵם בְּכִשְׁלוֹנָם. ד) וְהָאוֹמֵר אֶחְטָא וְאָשׁוּב וּבִכְלַל זֶה הָאוֹמֵר אֶחְטָא וְיוֹם הַכִּפּוּרִים מְכַפֵּר:
כסף משנה
1.
There are 24 deeds which hold back Teshuvah: Four are the commission of severe sins. God will not grant the person who commits such deeds to repent because of the gravity of his transgressions.
They are:
a) One who causes the masses to sin, included in this category is one who holds back the many from performing a positive command;
b) One who leads his colleague astray from the path of good to that of bad; for example, one who proselytizes or serves as a missionary [for idol worship];
c) One who sees his son becoming associated with evil influences and refrains from rebuking him. Since his son is under his authority, were he to rebuke him, he would have separated himself [from these influences]. Hence, [by refraining from admonishing him, it is considered] as if he caused him to sin.
Included in this sin are also all those who have the potential to rebuke others, whether an individual or a group, and refrain from doing so, leaving them to their shortcomings.
d) One who says: "I will sin and then, repent." Included in this category is one who says: "I will sin and Yom Kippur will atone [for me]."

הלכה ב
וּמֵהֶן חֲמִשָּׁה דְּבָרִים הַנּוֹעֲלִים דַּרְכֵי הַתְּשׁוּבָה בִּפְנֵי עוֹשֵׂיהֶן. וְאֵלּוּ הֵן. א) הַפּוֹרֵשׁ מִן הַצִּבּוּר, לְפִי שֶׁבִּזְמַן שֶׁיַּעֲשׂוּ תְּשׁוּבָה לֹא יִהְיֶה עִמָּהֶן וְאֵינוֹ זוֹכֶה עִמָּהֶן בִּזְכוּת שֶׁעוֹשִׂין. ב) וְהַחוֹלֵק עַל דִּבְרֵי חֲכָמִים, לְפִי שֶׁמַּחְלָקְתוֹ גּוֹרֶמֶת לוֹ לִפְרשׁ מֵהֶן וְאֵינוֹ יוֹדֵעַ דַּרְכֵי הַתְּשׁוּבָה. ג) וְהַמַּלְעִיג עַל הַמִּצְוֹת, שֶׁכֵּיוָן שֶׁנִּתְבַּזּוּ בְּעֵינָיו אֵינוֹ רוֹדֵף אַחֲרֵיהֶן וְלֹא עוֹשָׂן וְאִם לֹא יַעֲשֶׂה בַּמֶּה יִזְכֶּה. ד) וְהַמְבַזֶּה רַבּוֹתָיו, שֶׁדָּבָר זֶה גּוֹרֵם לוֹ לְדָחֳפוֹ וּלְטָרְדוֹ כְּגֵיחֲזִי וּבִזְמַן שֶׁנִּטְרָד לֹא יִמְצָא מְלַמֵּד וּמוֹרֶה לוֹ דֶּרֶךְ הָאֱמֶת. ה) וְהַשּׂוֹנֵא אֶת הַתּוֹכָחוֹת שֶׁהֲרֵי לֹא הִנִּיחַ לוֹ דֶּרֶךְ תְּשׁוּבָה. שֶׁהַתּוֹכָחָה גּוֹרֶמֶת לִתְשׁוּבָה שֶׁבִּזְמַן שֶׁמּוֹדִיעִין לוֹ לָאָדָם חֲטָאָיו וּמַכְלִימִין אוֹתוֹ חוֹזֵר בִּתְשׁוּבָה כְּמוֹ שֶׁכָּתוּב בַּתּוֹרָה (דברים ט ז) "זְכֹר (וְ) אַל תִּשְׁכַּח". (דברים ט ז) "מַמְרִים הֱיִיתֶם". (דברים כט ג) "וְלֹא נָתַן ה' לָכֶם לֵב". (דברים לב ו) "עַם נָבָל וְלֹא חָכָם". וְכֵן יְשַׁעְיָהוּ הוֹכִיחַ אֶת יִשְׂרָאֵל וְאָמַר (ישעיה א ד) "הוֹי גּוֹי חֹטֵא". (ישעיה א ג) "יָדַע שׁוֹר קֹנֵהוּ". (ישעיה מח ד) "מִדַּעְתִּי כִּי קָשֶׁה אָתָּה". וְכֵן צִוָּהוּ הָאֵל לְהוֹכִיחַ לַחַטָּאִים שֶׁנֶּאֱמַר (ישעיה נח א) "קְרָא בְגָרוֹן אַל תַּחְשֹׂךְ". וְכֵן כָּל הַנְּבִיאִים הוֹכִיחוּ לְיִשְׂרָאֵל עַד שֶׁחָזְרוּ בִּתְשׁוּבָה. לְפִיכָךְ צָרִיךְ לְהַעֲמִיד בְּכָל קָהָל וְקָהָל מִיִּשְׂרָאֵל חָכָם גָּדוֹל וְזָקֵן וִירֵא שָׁמַיִם מִנְּעוּרָיו וְאָהוּב לָהֶם שֶׁיְּהֵא מוֹכִיחַ לָרַבִּים וּמַחֲזִירָן בִּתְשׁוּבָה, וְזֶה שֶּׁשּׂוֹנֵא אֶת הַתּוֹכָחוֹת אֵינוֹ בָּא לַמּוֹכִיחַ וְלֹא שׁוֹמֵעַ דְּבָרָיו לְפִיכָךְ יַעֲמֹד בְּחַטֹּאתָיו שֶׁהֵם בְּעֵינָיו טוֹבִים:
כסף משנה
2.
Among [the 24] are five deeds which cause the paths of Teshuvah to be locked before those who commit them. They are:
a) One who separates himself from the community; when they repent, he will not be together with them and he will not merit to share in their merit.
b) One who contradicts the words of the Sages; the controversy he provokes will cause him to cut himself off from them and, thus, he will never know the ways of repentance.
c) One who scoffs at the mitzvoth; since he considers them as degrading, he will not pursue them or fulfill them. If he does not fulfill mitzvot, how can he merit [to repent]?
d) One who demeans his teachers; this will cause them to reject and dismiss him as [Elishah did to] Gechazi. In this period of rejection, he will not find a teacher or guide to show him the path of truth.
e) One who hates admonishment; this will not leave him a path for repentance. Admonishment leads to Teshuvah. When a person is informed about his sins and shamed because of them, he will repent. Accordingly, [rebukes are] included in the Torah, [for example]:
”Remember, do not forget, that you provoked [God, your Lord, in the desert. From the day you left Egypt until here,] you have been rebelling....”(Deuteronomy 9:7 .
”[Until this day,] God did not give you a heart to know....” (Deuteronomy 29:3 .
”[Is this the way you repay God,] you ungrateful, unwise nation” (Deuteronomy 2:6 .
Similarly, Isaiah rebuked Israel, declaring: “Woe, sinful nation, [people laden with iniquity...]” (Isaiah 1:4 ,
”The ox knows its owner, [and the ass, his master's crib. Israel does not know...]” (ibid.: 1:3),
I know you are obstinate... (ibid. 48:4).
God also commanded him to admonish the transgressors as [ibid. 58:1] states: "Call out from your throat, do not spare it." Similarly, all the prophets rebuked Israel until she repented. Therefore, it is proper for each and every congregation in Israel to appoint a great sage of venerable age, with [a reputation of] fear of heaven from his youth, beloved by the community, to admonish the masses and motivate them to Teshuvah.
This person who hates admonishment will not come to the preacher's [lecture] or hear his words. Accordingly, he will continue his sinful [paths], which he regards as good.

הלכה ג
וּמֵהֶם חֲמִשָּׁה דְּבָרִים הָעוֹשֶׂה אוֹתָן אִי אֶפְשָׁר לוֹ שֶׁיָּשׁוּב בִּתְשׁוּבָה גְּמוּרָה לְפִי שֶׁהֵם עֲוֹנוֹת שֶׁבֵּין אָדָם לַחֲבֵרוֹ וְאֵינוֹ יוֹדֵעַ חֲבֵרוֹ שֶׁחָטָא לוֹ כְּדֵי שֶׁיַּחֲזִיר לוֹ אוֹ יִשְׁאַל מִמֶּנּוּ לִמְחל לוֹ. וְאֵלּוּ הֵן. א) הַמְקַלֵּל אֶת הָרַבִּים וְלֹא קִלֵּל אָדָם יָדוּעַ כְּדֵי שֶׁיִּשְׁאַל מִמֶּנּוּ כַּפָּרָה. ב) וְהַחוֹלֵק עִם גַּנָּב, שֶׁלְּפִי שֶׁאֵינוֹ יוֹדֵעַ גְּנֵבָה זוֹ שֶׁל מִי הִיא אֶלָּא הַגַּנָּב גּוֹנֵב לָרַבִּים וּמֵבִיא לוֹ וְהוּא לוֹקֵחַ. וְעוֹד שֶׁהוּא מַחֲזִיק יַד הַגַּנָּב וּמַחְטִיאוֹ. ג) וְהַמּוֹצֵא אֲבֵדָה וְאֵינוֹ מַכְרִיז עָלֶיהָ עַד שֶׁיַּחֲזִירָהּ לִבְעָלֶיהָ, לְאַחַר זְמַן כְּשֶׁיַּעֲשֶׂה תְּשׁוּבָה אֵינוֹ יוֹדֵעַ לְמִי יַחֲזִיר. ד) וְהָאוֹכֵל שׁוֹר עֲנִיִּים וִיתוֹמִים וְאַלְמָנוֹת. אֵלּוּ בְּנֵי אָדָם אֻמְלָלִין הֵם וְאֵינָן יְדוּעִים וּמְפֻרְסָמִים וְגוֹלִים מֵעִיר לְעִיר וְאֵין לָהֶם מַכִּיר כְּדֵי שֶׁיֵּדַע שׁוֹר זֶה שֶׁל מִי הוּא וְיַחֲזִירֶנּוּ לוֹ. ה) וְהַמְקַבֵּל שֹׁחַד לְהַטּוֹת דִּין אֵינוֹ יוֹדֵעַ עַד הֵיכָן הִגִּיעַ הַטָּיָה זוֹ וְכַמָּה הִיא כֹּחָהּ כְּדֵי שֶׁיַּחֲזִיר, שֶׁהַדָּבָר יֵשׁ לוֹ רַגְלַיִם. וְעוֹד שֶׁהוּא מַחֲזִיק יַד זֶה וּמַחְטִיאוֹ:
כסף משנה
3.
Among these [24] are five [transgressions] for which it is impossible for the person who commits them to repent completely. They are sins between man and man, concerning which it is impossible to know the person whom one sinned against in order to return [what is owed him] or ask for his forgiveness. They are:
a) One who curses the many without cursing a specific individual from whom he can request forgiveness;
b) One who takes a share of a thief's [gain], for he does not know to whom the stolen article belongs. The thief steals from many, brings him [his share], and he takes it. Furthermore, he reinforces the thief and causes him to sin;
c) One who finds a lost object and does not announce it [immediately] in order to return it to its owners. Afterwards, when he desires to repent, he will not know to whom to return the article;
d) One who eats an ox belonging to the poor, orphans, or widows. These are unfortunate people, who are not well-known or recognized by the public. They wander from city to city and thus, there is no one who can identify them and know to whom the ox belonged in order that it may be returned to him.
e) One who takes a bribe to pervert judgment. He does not know the extent of the perversion or the power [of its implications] in order to pay the [people whom he wronged], for his judgment had a basis. Furthermore, [by taking a bribe], he reinforces the person [who gave it] and causes him to sin.

הלכה ד
וּמֵהֶן חֲמִשָּׁה דְּבָרִים הָעוֹשֶׂה אוֹתָן אֵין חֶזְקָתוֹ לָשׁוּב מֵהֶן. לְפִי שֶׁהֵם דְּבָרִים קַלִּים בְּעֵינֵי רֹב הָאָדָם וְנִמְצָא חוֹטֵא וְהוּא יְדַמֶּה שֶׁאֵין זֶה חֵטְא. וְאֵלּוּ הֵן. א) הָאוֹכֵל מִסְּעֻדָּה שֶׁאֵינָהּ מַסְפֶּקֶת לִבְעָלֶיהָ שֶׁזֶּה אֲבַק גֵּזֶל הוּא. וְהוּא מְדַמֶּה שֶׁלֹּא חָטָא וְיֹאמַר כְּלוּם אָכַלְתִּי אֶלָּא בִּרְשׁוּתוֹ. ב) הַמִּשְׁתַּמֵּשׁ בַּעֲבוֹטוֹ שֶׁל עָנִי שֶׁהָעֲבוֹט שֶׁל עָנִי אֵינוֹ אֶלָּא כְּגוֹן קוֹרְדוֹם וּמַחֲרֵשָׁה וְיֹאמַר בְּלִבּוֹ אֵינָן חֲסֵרִים וַהֲרֵי לֹא גָּזַלְתִּי אוֹתוֹ. ג) הַמִּסְתַּכֵּל בַּעֲרָיוֹת מַעֲלֶה עַל דַּעְתּוֹ שֶׁאֵין בְּכָךְ כְּלוּם שֶׁהוּא אוֹמֵר וְכִי בָּעַלְתִּי אוֹ קָרַבְתִּי אֶצְלָהּ. וְהוּא אֵינוֹ יוֹדֵעַ שֶׁרְאִיַּת הָעֵינַיִם עָוֹן גָּדוֹל שֶׁהִיא גּוֹרֶמֶת לְגוּפָן שֶׁל עֲרָיוֹת שֶׁנֶּאֱמַר (במדבר טו לט) "וְלֹא תָתֻרוּ אַחֲרֵי לְבַבְכֶם וְאַחֲרֵי עֵינֵיכֶם". ד) הַמִּתְכַּבֵּד בִּקְלוֹן חֲבֵרוֹ אוֹמֵר בְּלִבּוֹ שֶׁאֵינוֹ חֵטְא לְפִי שֶׁאֵין חֲבֵרוֹ עוֹמֵד שָׁם וְלֹא הִגִּיעַ לוֹ בּשֶׁת וְלֹא בִּיְּשׁוֹ אֶלָּא עָרַךְ מַעֲשָׂיו הַטּוֹבִים וְחָכְמָתוֹ לְמוּל מַעֲשֵׂה חֲבֵרוֹ אוֹ חָכְמָתוֹ כְּדֵי שֶׁיֵּרָאֶה מִכְּלָלוֹ שֶׁהוּא מְכֻבָּד וַחֲבֵרוֹ בָּזוּי. ה) וְהַחוֹשֵׁד כְּשֵׁרִים אוֹמֵר בְּלִבּוֹ שֶׁאֵינוֹ חֵטְא לְפִי שֶׁהוּא אוֹמֵר מֶה עָשִׂיתִי לוֹ וְכִי יֵשׁ שָׁם אֶלָּא חֲשָׁד שֶׁמָּא עָשָׂה אוֹ לֹא עָשָׂה וְהוּא אֵינוֹ יוֹדֵעַ שֶׁזֶּה עָוֹן שֶׁמֵּשִׂים אָדָם כָּשֵׁר בְּדַעְתּוֹ כְּבַעַל עֲבֵרָה:
כסף משנה
4.
Also among the [24] are five [transgressions] for which it is unlikely that the person who commits them will repent. Most people regard these matters lightly. Hence, [by committing such a transgression,] a person will sin without realizing that he has. They are:
a) One who eats from a meal which is not sufficient for its owners. This is a "shade of theft." However, the person who [partook from this meal] will not realize that he has sinned, for he will rationalize: "I only ate with his permission."
b) One who makes use of a pledge taken from a poor person. The pledge taken from a poor person would be his axe or plow. He rationalizes: "Their value will not depreciate and, hence, I haven't stolen anything from him."
c) One who looks at women forbidden to him. He considers the matter of little consequence, rationalizing: "Did I engage in relations with her? Was I intimate with her?" He fails to realize how looking [at such sights] is a great sin, for it motivates a person to actually take part in illicit sexual relations as implied by [Numbers 15:39] "Do not follow after your heart and your eyes."
d) One who takes pride in his colleague's shame. He tells himself that he has not sinned, for his colleague was not present. Thus, no shame came [directly] to his colleague, nor did he humiliate him. He merely contrasted his good deeds and wisdom against the deeds or wisdom of his colleague in order that, out of that comparison, he would appear honorable, and his colleague, shameful.
e) One who suspects worthy people. He will also say to himself "I haven't sinned," for he will rationalize: "What have I done to him? All I did was raise a doubt whether he committed the wrong or not." He does not realize that this is a sin, for he has considered a worthy person as a transgressor.

הלכה ה
וּמֵהֶן חֲמִשָּׁה דְּבָרִים הָעוֹשֶׂה אוֹתָם יִמָּשֵׁךְ אַחֲרֵיהֶם תָּמִיד וְקָשִׁים הֵם לִפְרשׁ מֵהֶן. לְפִיכָךְ צָרִיךְ אָדָם לְהִזָּהֵר מֵהֶן שֶׁמָּא יִדְבַּק בָּהֶן וְהֵן כֻּלָּן דֵּעוֹת רָעוֹת עַד מְאֹד. וְאֵלּוּ הֵן. רְכִילוּת. וְלָשׁוֹן הָרַע. וּבַעַל חֵמָה. וּבַעַל מַחֲשָׁבָה רָעָה. וְהַמִּתְחַבֵּר לָרָשָׁע מִפְּנֵי שֶׁהוּא לוֹמֵד מִמַּעֲשָׂיו וְהֵן נִרְשָׁמִים בְּלִבּוֹ. הוּא שֶׁאָמַר שְׁלֹמֹה (משלי יג כ) "וְרֹעֶה כְסִילִים יֵרוֹעַ". וּכְבָר בֵּאַרְנוּ בְּהִלְכוֹת דֵּעוֹת דְּבָרִים שֶׁצָּרִיךְ כָּל אָדָם לִנְהֹג בָּהֶן תָּמִיד, קַל וָחֹמֶר לְבַעַל תְּשׁוּבָה:
כסף משנה
5.
Among the [24] are five [qualities] which have the tendency to lead the transgressor to continue to commit them and which are very difficult to abandon. Therefore, a person should be very careful lest he become attached to them, for they are very bad attributes. They are:
a) gossip;
b) slander;
c) quick-temperedness;
d) a person preoccupied with sinister thoughts;
e) a person who becomes friendly with a wicked person, for he learns from his deeds and they are imprinted on his heart. This was implied by Solomon [Proverbs 13:20]: "A companion of fools will suffer harm."
In Hilchot De'ot, we explained the [character traits] which all people should continually follow. This surely holds true for a Baal-Teshuvah.

הלכה ו
כָּל אֵלּוּ הַדְּבָרִים וְכַיּוֹצֵא בָּהֶן אַף עַל פִּי שֶׁמְּעַכְּבִין אֶת הַתְּשׁוּבָה אֵין מוֹנְעִין אוֹתָהּ אֶלָּא אִם עָשָׂה אָדָם תְּשׁוּבָה מֵהֶן הֲרֵי זֶה בַּעַל תְּשׁוּבָה וְיֵשׁ לוֹ חֵלֶק לָעוֹלָם הַבָּא:
כסף משנה
6.
All of the above, and other similar transgressions, though they hold back repentance, they do not prevent it entirely. Should one of these people repent, he is a Baal-Teshuvah and has a portion in the world to come.

מדע הלכות תשובה פרק ד
Madda Teshuvah Chapter 4