(22) When you make a vow to Adonai your God, do not put off fulfilling it, for Adonai your God will require it of you, and you will have incurred guilt; (23) whereas you incur no guilt if you refrain from vowing. (24) You must fulfill what has crossed your lips and perform what you have voluntarily vowed to Adonai your God, having made the promise with your own mouth.
(1) לא תאחר לשלמו [WHEN YOU MAKE A VOW TO ADONAI YOUR GOD] DO NOT PUT OFF FULFILLING IT. — You have no more than the next three pilgrimage festivals to fulfill it, as the sages derived it from (the fact that one does not transgress the prohibition before three festivals elapse) from a Scriptural text (Rosh Hashanah 4b).
The Torah warned you to be careful before making vows, and remembers that though they constitute an incentive to bring a sacrifice, if you do make a vow, there is always the danger of committing a sin through neglecting or deferring its fulfillment, while if you do not vow at all, you have committed no sin.
Ramban
(3) When you make a vow to God, do not delay to fulfill it. For God has no pleasure in fools; what you vow, fulfill. (4) It is better not to vow at all than to vow and not fulfill. (5) Don’t let your mouth bring you into disfavor, and don’t plead before the messenger that it was an error, but fear God; else God may be angered by your talk and destroy your possessions.
The verse states that Adonai has no pleasure in fools who imagine they are doing God's will by making numerous vows in order to spur themselves to fulfill a precept. Lacking prudence and understanding, they do no stop to think that perhaps it may turn out impossible for them to fulfill them all. On the contrary, they imagine they will be credited with the good intention that they had at the time of the vow. For this reason, the verse continues, "Don’t let your mouth bring you into disfavor, and don’t plead before the messenger that it was an error": – do not indulge in making vows, and when you fail to fulfill them, say to the cruel angel who will be sent against you that it was all a mistake, that you sincerely meant to offer them but circumstances made it impossible to do so...
Ramban
א"ל רבא לרב נחמן חזי מר האי מרבנן דאתא ממערבא ואמר איזדקיקו ליה רבנן לבריה דרב הונא בר אבין ושרו ליה נדריה ואמרו ליה זיל ובעי רחמי על נפשך דחטאת דתני רב דימי אחוה דרב ספרא כל הנודר אע"פ שהוא מקיימו נקרא חוטא אמר רב זביד מאי קרא (דברים כג, כג) וכי תחדל לנדור לא יהיה בך חטא הא לא חדלת איכא חטא תניא האומר לאשתו כל נדרים שתדורי אי אפשי שתדורי אין זה נדר לא אמר כלום יפה עשית ואין כמותך ואם לא נדרת מדירך אני דבריו קיימין
Rava said to Rav Naḥman: Master, see that Sage who came from the West, Eretz Yisrael, and who said: The Sages attended to the dissolution of a vow taken by the son of Rav Huna bar Avin, and they dissolved his vow and said to him: Go and request mercy for yourself, for you have sinned by taking a vow. As Rav Dimi, the brother of Rav Safra teaches: With regard to anyone who takes a vow, even if he fulfills it, he is called a sinner. Rav Zevid said: What verse teaches this? It is: “But if you refrain to vow, it will be no sin in you” (Deuteronomy 23:23). It may be inferred that if you did not refrain from taking vows, there is sin.
(יג) כָּל נִדְרֵי
(יד) וֶאֱסָרֵי
(טו) וּשְׁבוּעֵי
(טז) וַחֲרָמֵי
(יז) וְקוֹנָמֵי
(יח) וְכִנּוּיֵי.
(יט) וְקִנוּסֵי
(כ) דִּנְדַֽרְנָא.
(כא) וּדְאִשְׁתַּבַּֽעְנָא.
(כב) וּדְאַחֲרִימְנָא.
(כג) וּדְאָסַֽרְנָא עַל נַפְשָׁתָֽנָא.
(כד) מִיּוֹם כִּפּוּרִים זֶה
(כה) עַד יוֹם כִּפּוּרִים
(כו) הַבָּא עָלֵֽינוּ לְטוֹבָה.
(כז) בְּכֻלְּהוֹן אִחֲרַֽטְנָא בְהוֹן.
(כח) כֻּלְּהוֹן יְהוֹן שָׁרָן.
(כט) שְׁבִיקִין, שְׁבִיתִין,
(ל) בְּטֵלִין וּמְבֻטָּלִין,
(לא) לָא שְׁרִירִין
(לב) וְלָא קַיָּמִין:
(לג) נִדְרָֽנָא לָא נִדְרֵי.
(לד) וֶאֱסָרָֽנָא
(לה) לָא אֱסָרֵי.
(לו) וּשְׁבוּעָתָֽנָא לָא שְׁבוּעוֹת:
(13) All vows,
(14) and things we have made forbidden on ourselves,
(15) and oaths,
(16) and items we have consecrated to the Temple,
(17) and vows issued with the expression “konum,”
(18) and vows which are abbreviated,
(19) and vows issued with the expression “kanos,”
(20) that we have vowed,
(21) and sworn,
(22) and dedicated,
(23) and made forbidden upon ourselves;
(24) from this Yom Kippur
(25) until next Yom Kippur—
(26) may it come to us at a good time—
(27) We regret having made them;
(28) may they all be permitted,
(29) forgiven, eradicated
(30) and nullified,
(31) and may they not be valid
(32) or exist any longer.
(33) Our vows shall no longer be vows,
(34) and our prohibitions
(35) shall no longer be prohibited,
(36) and our oaths are no longer oaths.
Kol Nidre
All vows –
resolves and commitments, vows of abstinence and terms of obligation,
sworn promises and oaths of dedication –
that we promise and swear to God, and take upon ourselves
from this Day of Atonement until the next Day of Atonement, may it find us well:
we regret them and for all of them, we repent.
Let all of them be discarded and forgiven, abolished and undone;
they are not valid and they are not binding.
Our vows shall not be vows; our resolves shall not be resolves;
and our oaths – they shall not be oaths.
Mishkan Hanefesh