Holding onto a grudge is like drinking poison and thinking it’s going to kill the other person.
-Origin unknown
Holding on to anger is like grasping a hot coal with the intent of throwing it at someone else; you are the one who gets burned.
-Suttas (Buddhist scriptures)
(ט) אֵין הַתְּשׁוּבָה וְלֹא יוֹם הַכִּפּוּרִים מְכַפְּרִין אֶלָּא עַל עֲבֵרוֹת שֶׁבֵּין אָדָם לַמָּקוֹם כְּגוֹן מִי שֶׁאָכַל דָּבָר אָסוּר אוֹ בָּעַל בְּעִילָה אֲסוּרָה וְכַיּוֹצֵא בָּהֶן. אֲבָל עֲבֵרוֹת שֶׁבֵּין אָדָם לַחֲבֵרוֹ כְּגוֹן הַחוֹבֵל אֶת חֲבֵרוֹ אוֹ הַמְקַלֵּל חֲבֵרוֹ אוֹ גּוֹזְלוֹ וְכַיּוֹצֵא בָּהֶן אֵינוֹ נִמְחַל לוֹ לְעוֹלָם עַד שֶׁיִּתֵּן לַחֲבֵרוֹ מַה שֶּׁהוּא חַיָּב לוֹ וִירַצֵּהוּ. אַף עַל פִּי שֶׁהֶחֱזִיר לוֹ מָמוֹן שֶׁהוּא חַיָּב לוֹ צָרִיךְ לְרַצּוֹתוֹ וְלִשְׁאל מִמֶּנּוּ שֶׁיִּמְחל לוֹ. אֲפִלּוּ לֹא הִקְנִיט אֶת חֲבֵרוֹ אֶלָּא בִּדְבָרִים צָרִיךְ לְפַיְּסוֹ וְלִפְגֹּעַ בּוֹ עַד שֶׁיִּמְחל לוֹ. לֹא רָצָה חֲבֵרוֹ לִמְחל לוֹ מֵבִיא לוֹ שׁוּרָה שֶׁל שְׁלֹשָׁה בְּנֵי אָדָם מֵרֵעָיו וּפוֹגְעִין בּוֹ וּמְבַקְּשִׁין מִמֶּנּוּ. לֹא נִתְרַצָּה לָהֶן מֵבִיא לוֹ שְׁנִיָּה וּשְׁלִישִׁית. לֹא רָצָה מְנִיחוֹ וְהוֹלֵךְ לוֹ וְזֶה שֶׁלֹּא מָחַל הוּא הַחוֹטֵא. וְאִם הָיָה רַבּוֹ הוֹלֵךְ וּבָא אֲפִלּוּ אֶלֶף פְּעָמִים עַד שֶׁיִּמְחל לוֹ:
(9) Teshuva and Yom Kippur only atone for transgression between man and God, such as one who eats a forbidden food, or has a forbidden sexual relationship, etc. But transgressions between man and his fellow, such as hurting his fellow, or cursing his fellow, or stealing from him, etc, those are never forgiven until he gives his fellow what he owes him, and [his fellow] is appeased. Even if he returned the money he owed his [fellow], he must appease him and ask him to forgive him. Even if he only perturbed his fellow verbally, he must make amends and meet with him until he forgives him. If his fellow does not wish to forgive him, he should bring a line of three people who are friends with him and they will approach him and ask [forgiveness] from him. If he does not give in to them, he must bring people a second and third time. If he still does not give in, they should leave him alone, and that person who did not forgive – he is the sinner. But if it was his teacher, he must come and go even a thousand times until he forgives him.
(י) אָסוּר לָאָדָם לִהְיוֹת אַכְזָרִי וְלֹא יִתְפַּיֵּס אֶלָּא יְהֵא נוֹחַ לִרְצוֹת וְקָשֶׁה לִכְעֹס וּבְשָׁעָה שֶׁמְּבַקֵּשׁ מִמֶּנּוּ הַחוֹטֵא לִמְחל מוֹחֵל בְּלֵב שָׁלֵם וּבְנֶפֶשׁ חֲפֵצָה. וַאֲפִלּוּ הֵצֵר לוֹ וְחָטָא לוֹ הַרְבֵּה לֹא יִקֹּם וְלֹא יִטֹּר. וְזֶהוּ דַּרְכָּם שֶׁל זֶרַע יִשְׂרָאֵל וְלִבָּם הַנָּכוֹן. אֲבָל הָעוֹבְדֵי כּוֹכָבִים עַרְלֵי לֵב אֵינָן כֵּן אֶלָּא (וְעֶבְרָתָן) [וְעֶבְרָתוֹ] שְׁמָרָה נֶצַח. וְכֵן הוּא אוֹמֵר עַל הַגִּבְעוֹנִים לְפִי שֶׁלֹּא מָחֲלוּ וְלֹא נִתְפַּיְּסוּ וְהַגִּבְעֹנִים לֹא מִבְּנֵי יִשְׂרָאֵל הֵמָּה:
(יא) הַחוֹטֵא לַחֲבֵרוֹ וּמֵת חֲבֵרוֹ קֹדֶם שֶׁיְּבַקֵּשׁ מְחִילָה מֵבִיא עֲשָׂרָה בְּנֵי אָדָם וּמַעֲמִידָן עַל קִבְרוֹ וְיֹאמַר בִּפְנֵיהֶם חָטָאתִי לַה' אֱלֹהֵי יִשְׂרָאֵל וְלִפְלוֹנִי זֶה שֶׁכָּךְ וְכָךְ עָשִׂיתִי לוֹ. וְאִם הָיָה חַיָּב לוֹ מָמוֹן יַחֲזִירוֹ לַיּוֹרְשִׁים. לֹא הָיָה יוֹדֵעַ לוֹ יוֹרְשִׁין יַנִּיחֶנּוּ בְּבֵית דִּין וְיִתְוַדֶּה:
(10) It is forbidden for a person to be cruel and not make amends; instead, a person should get appeased easily and get angry slowly. And at the moment when the sinner asks for forgiveness – forgive with a whole heart and a desirous soul. And even if he pained him and sinned against him many times, he should not take revenge or hold a grudge -- that is the way of the Children of Israel and their correct hearts. But the nations of uncircumcised heart are not so, but are rather (Amos 1:11) "and he kept his wrath for ever." And similarly it is said about the Gibonites, who did not forgive Israel, (II Samuel 21:2) "the Gibonites are not of the children of Israel" [because they do not forgive, a sign of cruelty].
(11) Someone who sins against his fellow, and the fellow dies before he can ask him for forgiveness, he should bring ten people and stand them by his grave and say in front of them, “I have sinned against the Lord, God of Israel and against this certain person because I did such-and-such to him.” And if he owed him money, he should give it to his heirs. If he does not know who the heirs are he should give it to the court and confess.