Halacha

הלכה א
קָטָן בֶּן שְׁתֵּים עֶשְׂרֵה שָׁנָה וְיוֹם אֶחָד וּקְטַנָּה בַּת אַחַת עֶשְׂרֵה שָׁנָה וְיוֹם אֶחָד שֶׁנִּשְׁבְּעוּ אוֹ נָדְרוּ בֵּין נִדְרֵי אִסָּר בֵּין נִדְרֵי הֶקְדֵּשׁ בּוֹדְקִין אוֹתָן וְשׁוֹאֲלִין אוֹתָן. אִם יוֹדְעִין לְשֵׁם מִי נָדְרוּ וּלְשֵׁם מִי הִקְדִּישׁוּ וְנִשְׁבְּעוּ נִדְרֵיהֶן קַיָּמִים וְהֶקְדֵּשָׁן הֶקְדֵּשׁ. וְאִם לֹא יָדְעוּ אֵין בְּנִדְרֵיהֶם וּבְדִבְרֵיהֶם כְּלוּם. וּצְרִיכִין בְּדִיקָה כָּל הַשָּׁנָה כֻּלָּהּ שֶׁהִיא שְׁנַת י''ב לִקְטַנָּה. וּשְׁנַת י''ג לְקָטָן:
כסף משנה
1.
[The following rules apply with regard to] a male minor who is twelve years and one day old1As explained by the commentaries, in this context, we follow the principle: "A portion of a day is considered as an entire day." Thus, directly after his twelfth birthday, as soon as a male child enters into his thirteenth year of life, these laws apply to him. Similar concepts apply with regard to a female minor. and a female minor who is eleven years and one day old who took an oath or a vow, whether a vow forbidding something to them or a vow consecrating an article. We investigate them and ask them [questions]. If they know for Whose sake they took the vow2For a vow must be taken for God's sake, as Numbers 30:3 states: "When a man will take a vow to God." or for Whose sake they consecrated [the article] or took the oath, their vows and their consecration are binding.3This is a unique concept that Niddah 45b derives from the exegesis of Leviticus 27:2. Although throughout Jewish law, until a male attains the age of thirteen and a female, the age of twelve, their actions are of no consequence according to Scriptural Law, an exception is made in this instance because of the above verse, as stated in Halachah 4. If they do not know, their vows and their statements are of no consequence.
It is necessary to make an investigation throughout the entire twelfth year of a female minor and the entire thirteenth year of a male minor.4As explained in the following halachah.

הלכה ב
כֵּיצַד. הֲרֵי שֶׁנָּדְרוּ אוֹ הִקְדִּישׁוּ בִּתְחִלַּת שָׁנָה זוֹ וְשָׁאֲלוּ אוֹתָן וְנִמְצְאוּ יוֹדְעִין וְנִתְקַיֵּם נִדְרָן וְנָדְרוּ נֵדֶר אַחֵר אֲפִלּוּ בְּסוֹף שָׁנָה זוֹ צְרִיכִין בְּדִיקָה וְאַחַר כָּךְ יִתְקַיֵּם. וְאֵין אוֹמְרִין הוֹאִיל וְנִמְצְאוּ יוֹדְעִין בִּתְחִלַּת הַשָּׁנָה אֵין צְרִיכִין בְּדִיקָה אֶלָּא בּוֹדְקִין אוֹתָן אֶת כָּל הַשָּׁנָה הַזּוֹ כֻּלָּהּ:
כסף משנה
2.
What is implied? A minor took a vow or consecrated [property] at the beginning of the year, they were questioned, it was discovered that they knew [for Whose sake the vow was taken], and the vow was maintained. If they took another vow, even at the end of this year, they must be questioned again [for the vow] to be maintained. We do not say: "Since they were knowledgeable at the beginning of the year, they no longer have to be questioned. Instead, we question them throughout the entire year.5The Kessef Mishneh questions the Rambam's ruling, noting that Niddah, loc. cit., the source for this halachah, does not lead to such a conclusion. He suggests that perhaps the Rambam had a different version of that text. Yayin Malchut states that this resolution is reflected in the revised version of the Rambam's Commentary to the Mishnah (Niddah 5:6). In his initial explanation of the mishnah, he appeared to follow the same text as the popular version of the Talmud, but later in life, he revised that interpretation, accepting a different version of the text. The Rambam's rationale is that since we are speaking about a minor, it is possible that his level of understanding will fluctuate.

הלכה ג
קֹדֶם הַזְּמַן הַזֶּה אַף עַל פִּי שֶׁאָמְרוּ יוֹדְעִין אָנוּ לְשֵׁם מִי נָדַרְנוּ וּלְשֵׁם מִי הִקְדַּשְׁנוּ אֵין נִדְרֵיהֶן נֵדֶר וְאֵין הֶקְדֵּשָׁן הֶקְדֵּשׁ. וְאַחַר הַזְּמַן הַזֶּה שֶׁנִּמְצָא הַבֵּן בֶּן י''ג שָׁנָה וְיוֹם אֶחָד וְהַבַּת בַּת י''ב שָׁנָה וְיוֹם אֶחָד אַף עַל פִּי שֶׁאָמְרוּ אֵין אָנוּ יוֹדְעִין לְשֵׁם מִי נָדַרְנוּ וּלְשֵׁם מִי הִקְדַּשְׁנוּ דִּבְרֵיהֶן קַיָּמִין וְהֶקְדֵּשָׁן הֶקְדֵּשׁ וְנִדְרֵיהֶן נְדָרִים וְאַף עַל פִּי שֶׁלֹּא הֵבִיאוּ שְׁתֵּי שְׂעָרוֹת. וְזוֹ הִיא עוֹנַת נְדָרִים הָאֲמוּרָה בְּכָל מָקוֹם:
כסף משנה
3.
Before this time, even when they say: "We know for Whose sake we took the vow or for Whose sake we consecrated it," their vows and their consecration are of no consequence. After this time [passes] and a male is thirteen years and one day and a female is twelve years and one day,6I.e., their thirteenth and twelfth birthdays arrive as stated in note 1.
In his Commentary to the Mishnah (Niddah 5:6), the Rambam writes that the Torah made the age for which women become responsible for their vows less than the age men become responsible, generally, a woman's lifetime is less than that of a man.
even though they say: "We do not know for Whose sake we took the vow or for Whose sake we consecrated it,"7If they manifested signs that they are mentally or emotionally incapable, this law does not apply. If, however, they are merely somewhat slow and do not understand the concept of vows, their vows are of consequence, because they have already reached the age when one becomes responsible for his or her actions. their vows and their consecration are binding even if they did not manifest physical signs of maturity.8I.e., two pubic hairs as stated in Hilchot Ishut 2:1. This is the time when vows [take effect] which is mentioned in all sources.9There are others who maintain that the expression "the time when vows [take effect]" refers to a minor who understands the meaning of his vows as stated in Halachah 1. The Rambam prefers his interpretation, because it is dependent on time, the child's age, while the first interpretation is dependent on the child's knowledge (Yayim Malchut).

הלכה ד
הוֹאִיל וְהִגִּיעוּ לִשְׁנֵי הַגְּדוֹלִים נִדְרֵיהֶן קַיָּמִין. אַף עַל פִּי שֶׁלֹּא הֵבִיאוּ סִימָנִין וַעֲדַיִן לֹא נַעֲשׂוּ גְּדוֹלִים לְכָל דָּבָר. וְדָבָר זֶה מִדִּבְרֵי תּוֹרָה שֶׁהַמֻּפְלָא הַסָּמוּךְ לְאִישׁ הֶקְדֵּשׁוֹ וְנִדְרוֹ נֵדֶר. אַף עַל פִּי שֶׁנִּדְרֵיהֶן קַיָּמִין אִם חִלְּלוּ נִדְרָן אוֹ נִשְׁבְּעוּ וְהֶחְלִיפוּ אֵינָן לוֹקִין עַד שֶׁיַּגְדִּילוּ וְיָבִיאוּ שְׁתֵּי שְׂעָרוֹת:
כסף משנה
4.
Since they reached the age of majority, their vows are binding even if they did not manifest physical signs of majority and [thus] are not considered as adults with regard to all matters. This concept is of Scriptural origin:10This is the subject of debate among the Rishonim, for some do not accept the Rambam's view. that when a person close to the age of adulthood utters a vow, his consecration [of articles] and his vows are binding. Nevertheless, although the vows of these individuals are binding, if they desecrate their vows or take oaths and substitute for them, they are not punishable by lashes until they reach the age of majority and manifest signs of physical maturity.11For until the latter age, they are still minors, and minors are not liable for punishment for transgressions that they perform.

הלכה ה
הִקְדִּישׁוּ וּבָא הַגָּדוֹל וְנֶהֱנָה מִן הַהֶקְדֵּשׁ שֶׁהִקְדִּישׁוּ לוֹקֶה מִשּׁוּם שֶׁנִּדְרֵיהֶם נְדָרִים מִן הַתּוֹרָה כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
5.
If [such a minor] consecrated an article and an adult came and benefited from the article that he consecrated, [the adult] is liable for lashes.12For violating the prohibition against benefiting from consecrated property (Hilchot Meilah 1:3). For [the minor's] vows are valid according to Scriptural Law, as explained.13In the previous halachah. Since the child's consecration is valid, the article has the status of a consecrated article according to Scriptural Law and a person who misappropriates it is liable.

הלכה ו
בַּמֶּה דְּבָרִים אֲמוּרִים שֶׁבַּת י''ב שָׁנָה וְיוֹם אֶחָד נְדָרֶיהָ קַיָּמִין. בְּשֶׁלֹּא הָיְתָה בִּרְשׁוּת הָאָב אוֹ בִּרְשׁוּת הַבַּעַל. אֲבָל אִם הָיְתָה בִּרְשׁוּת הָאָב אֲפִלּוּ הִגְדִּילָה וַהֲרֵי הִיא נַעֲרָה. אָבִיהָ מֵפֵר כָּל נְדָרֶיהָ וְכָל שְׁבוּעוֹת שֶׁתִּשָּׁבַע בְּיוֹם שָׁמְעוֹ שֶׁנֶּאֱמַר (במדבר ל ו) "כָּל נְדָרֶיהָ וֶאֱסָרֶיהָ" וְגוֹ' (במדבר ל ו) "כִּי הֵנִיא אָבִיהָ אֹתָהּ" וְגוֹ':
כסף משנה
6.
When does the above statement - that the vows taken by a female twelve years and one day old are binding - apply? When she is neither in her father's domain14I.e., her father died. Alternatively, she was married as a minor and then she was divorced or widowed (see Halachah 25). Otherwise, she remains in his domain until the age of twelve and a half, as stated in the following halachah. or her husband's domain. If, however, she is in her father's domain, even if she comes of age and she is a maiden,15I.e., from the age of twelve until the age of twelve and a half. her father may nullify16See Chapter 13, Halachah 2, which describes how the father nullifies his daughter's vow. all17As the Shulchan Aruch (Yoreh De'ah 234:1) states, this applies even to vows taken dependent on the consent of others which cannot be repealed by a sage. of the vows and oaths she takes on the day he hears of them, as [Numbers 30:6] states: "All of her vows and prohibitions18The HaEmek HaShaalah interprets this term as referring to oaths.... [shall not stand...] because her father withheld her."

הלכה ז
וְעַד מָתַי אָבִיהָ מֵפֵר עַד שֶׁתִּבְגַּר. בָּגְרָה אֵינוֹ מֵפֵר לָהּ וַהֲרֵי כָּל נְדָרֶיהָ וּשְׁבוּעוֹתֶיהָ כְּנֵדֶר אַלְמָנָה וּגְרוּשָׁה שֶׁנֶּאֱמַר בָּהֶן (במדבר ל י) "כּל אֲשֶׁר אָסְרָה עַל נַפְשָׁהּ" וְגוֹ':
כסף משנה
7.
Until when may her father nullify [her vows]? Until she fully comes of age.19I.e., reaches the age of twelve and a half after manifesting physical signs of maturity (Hilchot Ishut 2:2). Once she fully comes of age, he may not nullify her [vows].20Numbers 30:17 gives him this privilege "during her maidenhood," i.e., and not beyond that time period (Kessef Mishneh). Instead, all of her vows and oaths are like those of a widow or a divorcee, as [implied by Numbers 30:10]: "Everything that she forbade upon her soul [shall remain upon her]."

הלכה ח
וּמֵאֵימָתַי מֵפֵר הַבַּעַל נִדְרֵי אִשְׁתּוֹ וּשְׁבוּעוֹתֶיהָ מִשֶּׁתִּכָּנֵס לַחֻפָּה. וְהוּא מֵפֵר לְעוֹלָם עַד שֶׁיְּגָרְשֶׁנָּה וְיַגִּיעַ הַגֵּט לְיָדָהּ. הָיְתָה מְגֹרֶשֶׁת מִסָּפֵק לֹא יָפֵר לָהּ. נָתַן לָהּ גֵּט עַל תְּנַאי אוֹ לְאַחַר זְמַן לֹא יָפֵר בַּיָּמִים שֶׁבֵּינְתַיִם. וְכֵן מִי שֶׁשָּׁמְעָה שֶׁמֵּת בַּעְלָהּ וְנִשֵּׂאת וַהֲרֵי בַּעְלָהּ קַיָּם וְכַיּוֹצֵא בָּהּ אֵין הַבַּעַל הָרִאשׁוֹן וְלֹא הָאַחֲרוֹן מְפֵרִין נְדָרֶיהָ. הָיְתָה מֵחַיָּבֵי לָאוִין וְאֵין צָרִיךְ לוֹמַר מֵחַיָּבֵי עֲשֵׂה וְהֵפֵר נְדָרֶיהָ הֲרֵי אֵלּוּ מוּפָרִין:
כסף משנה
8.
When may a husband nullify his wife's vows and oaths? From the time she enters the chupah.21I.e, from the beginning of the second sage of the marriage relationship known as nissuin. At that time, he takes her into a private room and from that time onward, the couple live as man and wife (Hilchot Ishut 10:1). During the first stage of the marriage relationship (erusin), when the erus has merely consecrated his wife, he does not have the right to nullify her vows alone (see Halachah 9). (In the present era, it is customary to perform both these stages of marriage directly after each other.) He may continue to nullify her vows forever until he divorces her, with the bill of divorce reaching her hand.22Implied is that if he sends the bill of divorce to her via an agent, he may nullify her vows until the bill of divorce enters her possession (Siftei Cohen 234:6, Turei Zahav 234:1).
If there was an unresolved doubt concerning her divorce,23I.e., he had a bill of divorce given to her and our Rabbis could not resolve if the manner in which the bill of divorce was given or written is effective. See Hilchot Gerushin 5:13 for an example.
The rationale for this law is that our Sages understood that the reason the Torah gave a husband the right to nullify his wife's vows was so that she would not become unattractive to him (Yevamot 90b). In this instance, he is not concerned that she becomes unattractive (Radbaz).
he should not nullify her vows. If he gives her a bill of divorce conditionally24See Hilchot Gerushin 8:1. or one that takes effect at a later time,25He tells her: "Here is your bill of divorce, but it does not take effect for 30 days" (ibid. 9:1). he should not nullify [her vows] in the interim.26I.e., in the days before the vow takes effect. The Siftei Cohen 234:8 states that even after the fact, the nullification does not take effect. Similarly, [when a woman] has heard that her husband died and remarried, but [in truth] her husband was alive27See Hilchot Gerushin 10:5 which describes this situation at length. or other similar situations [prevail],28E.g., a woman who went through a divorce and then remarried, but then it was discovered that her divorce was invalid (ibid.:7). In both this and the previous instance, both husbands are required to divorce the woman. neither her first husband, nor her second husband should nullify her vows.29The rationale for this and the previous laws is that our Sages understood that the reason the Torah gave a husband the right to nullify his wife's vows was so that she would not become unattractive to him. In this instance, since he is obligated to divorce her, it is desirable that she become unattractive to him (Yevamot, loc. cit.). If she was forbidden [to her husband] by a negative commandment30I.e., a negative commandment that is not punishable by execution, death at the hand of heaven, or karet. See Hilchot Ishut 1:7. and needless to say, if she is forbidden only by a positive commandment,31E.g., marriages like that of a non-virgin to a High Priest, which are not prohibited by a negative commandment. Instead, the prohibition is understood, because there is a positive commandment instructing the opposite. See ibid.:8. and her husband nullified her vows, her vows are nullified.32Although these marriages are forbidden, since they are still binding, the husband has this privilege.

הלכה ט
נַעֲרָה מְאֹרָסָה אֵין מֵפֵר נְדָרֶיהָ אֶלָּא הָאָב עִם הַבַּעַל כְּאַחַד. וְאִם הֵפֵר הָאֶחָד לְבַדּוֹ אֵינוֹ מוּפָר. הֵפֵר הַבַּעַל לְבַדּוֹ וְעָבְרָה עַל נִדְרָהּ קֹדֶם שֶׁיָּפֵר הָאָב אֵינָהּ לוֹקָה:
כסף משנה
9.
When a maiden33I.e., a girl between the ages of twelve and twelve and a half. has been consecrated, her vows may be nullified only by her father and the erus34The term erus means "the man who consecrated her." The Rambam does not use this term, but instead, the term baal meaning "husband." We, however, have used the term erus, because the term baal usually implies that nisuin, the second stage of marriage, has already taken place. together.35Numbers 30:17 states: "These are the statutes... between a man and his wife, between a father and his daughter in her youth." Nedarim 68a interprets the verse as referring to one woman, implying that the nullification of her vows is performed by her father and her erus together. In his Commentary to the Mishnah (Nedarim 9:9), the Rambam writes that from the Biblical text, it might appear that both the father and the erus have the right to nullify her vows independently. Hence, it is necessary to clarify that this is not so. If one nullified [a vow] alone, it is not nullified. If her erus nullified [the vow] alone and she violated the vow before her father nullified it, she is not liable for lashes.36Nedarim 68a states that since one of the two has already nullified the vow, it is weak and its violation is not punishable by lashes.

הלכה י
מֵת הָאָרוּס חָזְרָה לִרְשׁוּת אָבִיהָ. וְכָל שֶׁתִּדֹּר הָאָב מֵפֵר כְּשֶׁהָיָה קֹדֶם שֶׁתִּתְאָרֵס. מֵת הָאָב אַחַר שֶׁנִּתְאָרְסָה וְנָדְרָה אַחַר מוֹתוֹ אֵין הַבַּעַל מֵפֵר שֶׁאֵין הַבַּעַל מֵפֵר נִדְרֵי אִשְׁתּוֹ עַד שֶׁתִּכָּנֵס לַחֻפָּה:
כסף משנה
10.
If (the erus) dies, she returns to her father's domain. Any vow she takes37Even the vows she took previously while consecrated [Shulchan Aruch (Yoreh De'ah 234:11)]. This applies even if she has a yevam (Halachah 24). may be nullified by her father as was her status before consecration.38As stated in Halachah 6. If her father died after she was consecrated and she took a vow after his death, her erus cannot nullify it. For an erus cannot nullify his wife's vows [alone] until she enters the chupah.39Before nissuin, an erus can nullify his wife's vows only together with her father and that is impossible in this instance. See also Halachah 16.

הלכה יא
נַעֲרָה אֲרוּסָה שֶׁנָּדְרָה וְשָׁמַע אָבִיהָ וְלֹא שָׁמַע אֲרוּסָהּ וְנִתְגָרְשָׁה בּוֹ בַּיּוֹם וְנִתְאָרְסָה לְאַחֵר בּוֹ בַּיּוֹם אֲפִלּוּ לְמֵאָה אָבִיהָ וּבַעְלָהּ הָאַחֲרוֹן מְפֵרִין נְדָרֶיהָ שֶׁנָּדְרָה בִּפְנֵי אָרוּס רִאשׁוֹן. מִפְּנֵי שֶׁלֹּא יָצָאתָה לִרְשׁוּת עַצְמָהּ שָׁעָה אַחַת שֶׁעֲדַיִן הִיא בִּרְשׁוּת הָאָב מִפְּנֵי שֶׁהִיא נַעֲרָה:
כסף משנה
11.
[The following rules apply when] a consecrated maiden takes a vow, her father heard her vow, but not her erus,40For if her first erus heard her vow and did not nullify it, her father can no longer nullify it together with her second erus. See Halachah 17. she was divorced that day and then consecrated by another person41Or consecrated again by her first erus [Shulchan Aruch (Yoreh De'ah 234:13)]. that day.42It is necessary that the divorce(s) and the consecration(s) take place on the same day the father heard of and nullified the vow. For if not, the woman's last erus will not have the right to nullify the vow, as indicated by Chapter 12, Halachah 17. Even if [she was divorced and consecrated] 100 times [that day], her father and her last erus may nullify the vows she took before her first erus. [The rationale is that] she never departed into her own domain for one moment,43In contrast to the laws applying to a married woman, as stated in the following halachah. for throughout the entire time, she is in her father's domain, for she is still a maiden.

הלכה יב
אֲבָל הָאִשָּׁה הַנְּשׂוּאָה שֶׁנָּדְרָה וְלֹא הֵפֵר לָהּ בַּעְלָהּ וְגֵרְשָׁהּ בּוֹ בַּיּוֹם וְהֶחֱזִירָהּ בּוֹ בַּיּוֹם אֵינוֹ יָכוֹל לְהָפֵר שֶׁהֲרֵי יָצָאתָה לִרְשׁוּת עַצְמָהּ אַחַר שֶׁנָּדְרָה. אַף עַל פִּי שֶׁנָּדְרָה בִּרְשׁוּתוֹ וְהִיא עַתָּה בִּרְשׁוּתוֹ הוֹאִיל וְיָצְתָה בִּרְשׁוּת עַצְמָהּ בֵּינְתַיִם נִתְקַיְּמוּ נְדָרֶיהָ:
כסף משנה
12.
When, by contrast, a married woman took a vow and her husband did not nullify it, he divorced her that day, and remarried her that day, he cannot nullify her vows,44Nor may her father nullify her vows, for once she marries, her father no longer has the right to nullify her vows. for she departed into her independent domain after she took her vow.45Once a woman becomes independent for even one moment, her future husband cannot nullify the vows she took previously. Although she took her vow in his domain and she is now in his domain, since she departed into her own domain in the interim, her vows are binding.

הלכה יג
נַעֲרָה מְאֹרָסָה שֶׁנָּדְרָה וְלֹא שָׁמַע אָבִיהָ וְלֹא בַּעְלָהּ וְנִתְגָרְשָׁה וְנִתְאָרְסָה לַאֲחֵרִים. אֲפִלּוּ לְאַחַר כַּמָּה יָמִים כְּשֶׁיִּשְׁמַע הָאָב וְהַבַּעַל הָאַחֲרוֹן מְפֵרִין נְדָרֶיהָ שֶׁנָּדְרָה בִּפְנֵי אָרוּס הָרִאשׁוֹן הוֹאִיל וְלֹא שָׁמַע אוֹתָם הָאָרוּס הָרִאשׁוֹן:
כסף משנה
13.
[The following rule applies when] a consecrated maiden took a vow that was not heard by either her father or her erus,46If, however, either her erus or her father heard her vow when it was taken, it cannot be nullified at a later date. she was divorced, and then consecrated to someone else.47Since she remains partially in her father's domain, the divorce does not effect the right of her father and her present erus to nullify her vows. Even several days after [she took the vow], when her father and her last erus hear about the vow that she took while consecrated to her first erus, they may nullify it, since her first erus did not hear it.

הלכה יד
נַעֲרָה מְאֹרָסָה שֶׁנָּדְרָה וְשָׁמַע אָבִיהָ לְבַדּוֹ וְהֵפֵר לָהּ וּמֵת הָאָרוּס קֹדֶם שֶׁיִּשְׁמַע וְנִתְאָרְסָה בּוֹ בַּיּוֹם אֲפִלּוּ לְמֵאָה אָבִיהָ וַאֲרוּסָהּ הָאַחֲרוֹן מְפֵרִין נְדָרֶיהָ שֶׁנָּדְרָה בִּפְנֵי אָרוּס רִאשׁוֹן שֶׁמֵּת קֹדֶם שֶׁיִּשְׁמַע:
כסף משנה
14.
[The following rule applies when] a consecrated maiden took a vow, her father alone heard it and nullified it, but the man to whom she was consecrated died before hearing it. If she was consecrated to another man - or to 100 other men - that day48The consecration and the nullification of the vow must take place on the day that the father heard of the vow and nullified it (Turei Zahav 234:22). her father and her last erus may nullify her vow.49Since her first erus did not hear of her vow, the fact that he died before nullifying it does not deprive her last erus of that right. The father cannot nullify her vow alone, because it was taken when she was consecrated. Since her father nullified the vow, the right of her erus to nullify the vow is weak and of little substance. Accordingly, the right to nullify it cannot be transferred to the father alone, as in Halachah 16.
The Shulchan Aruch (Yoreh De'ah 234:16) quotes the Rambam's view, but also that of the Tur which maintains that the second erus can never nullify a vow together with the father.

הלכה טו
שָׁמַע אָרוּס רִאשׁוֹן וְהֵפֵר וּמֵת וְאַחַר כָּךְ שָׁמַע הָאָב וְנִתְאָרְסָה לְאַחֵר בּוֹ בַּיּוֹם אָבִיהָ עִם הָאָרוּס הָאַחֲרוֹן מְפֵרִין נְדָרֶיהָ:
כסף משנה
15.
[The following rule applies when] the erus heard [her vow], nullified it and died and afterwards,50I.e., after the death of her erus. her father heard and she was consecrated to another person that day.51But not on the following day. The Radbaz explains that this is speaking about a situation when the father heard of the vow on the same day as her first erus, for the nullification must be completed on the same day that he heard of the vow. If, however, her father does not hear about it until the following day and she was consecrated then, he and her new erus may nullify her vow then. Her father and the second erus may nullify her vows.52The Turei Zahav 234:13 maintains that the Rambam would also give her father the right to nullify the vow alone, because her first erus also heard the vow and did not maintain it (see the following halachah). The Rambam mentions her being consecrated by another person only to teach that if, this is indeed the situation, the second erus must also nullify the vow.

הלכה טז
שָׁמַע אָבִיהָ וְלֹא שָׁמַע הָאָרוּס וּמֵת בּוֹ בַּיּוֹם הָאָרוּס אוֹ שֶׁשָּׁמַע גַּם הָאָרוּס וְהֵפֵר אוֹ שֶׁשָּׁתַק וּמֵת בּוֹ בַּיּוֹם נִתְרוֹקְנָה רְשׁוּת לָאָב וְהָאָב יָכוֹל לְהָפֵר. שָׁמַע הָאָרוּס וְקִיֵּם וּמֵת בּוֹ בַּיּוֹם אוֹ שֶׁשָּׁמַע וְשָׁתַק וּמֵת בַּיּוֹם שֶׁלְּאַחֲרָיו אֵין הָאָב יָכוֹל לְהָפֵר:
כסף משנה
16.
If her father heard [that she took a vow], but the erus did not and the erus died that day or the erus also heard [about her vow] and nullified it or remained silent53Since he did not maintain the vow and died before the day was completed, we say that there was a possibility that he would nullify it. Hence, her father is given the right to nullify it. and then died that day, she returns to her father's domain and her father may nullify [her vows].54Since her erus no longer exists and he did not maintain the vow, the right to nullify is given to her father. In his gloss to Halachah 19, the Radbaz explains the apparent contradiction between these two halachot by stating that this halachah refers to an instance where the father did not nullify the vow before the erus died. Accordingly, the right of the erus to nullify the vow is not weakened. Hence it can be transferred to the father. Halachah 19 refers to a situation where the father nullified the vow and weakens it, as explained above.
If the erus heard [about her vow] and maintained it and died that day, or remained silent and died the following day,55Since he did not nullify it on the day that he heard it, he cannot nullify again. It is considered as if he maintained it. Once he maintained it, her father cannot nullify it. her father cannot nullify her vow.

הלכה יז
גֵּרְשָׁהּ הָאָרוּס אַחַר שֶׁשָּׁמַע. הֲרֵי זֶה סָפֵק אִם הַגֵּרוּשִׁין כִּשְׁתִיקָה וְיָפֵר הָאָב עִם הַבַּעַל הָאַחֲרוֹן שֶׁיְּאָרֵס בּוֹ בַּיּוֹם אוֹ הַגֵּרוּשִׁין כְּמוֹ שֶׁקִּיֵּם אָרוּס רִאשׁוֹן שֶׁכְּבָר נִתְקַיְּמוּ הַנְּדָרִים:
כסף משנה
17.
If the erus, divorced her after hearing [of her vow], there is an unresolved question whether the divorce is considered as silence and her father may nullify her vow together with a second erus who consecrates her that day.56I.e., combining Halachah 15 which states that the father and the second erus can nullify the vow and Halachah 16 which states that silence is equivalent to nullification. If she does not become consecrated again, the father can nullify the vow alone (Turei Zahav, loc. cit.). Or perhaps the divorce is like her first erus maintaining her vow, in which instance, the vow is maintained.57And cannot be nullified afterwards.

הלכה יח
שָׁמַע הָאָב וְהֵפֵר לָהּ וּמֵת הָאָב וְאַחַר כָּךְ שָׁמַע הַבַּעַל אֲפִלּוּ שָׁמַע הַבַּעַל קֹדֶם שֶׁיָּמוּת הָאָב לֹא נִתְרוֹקְנָה רְשׁוּת לַבַּעַל וְאֵינוֹ יָכוֹל לְהָפֵר לְעוֹלָם אַחַר מוֹת הָאָב. שֶׁאֵין הָאָרוּס מֵפֵר אֶלָּא בְּשֻׁתָּפוּת:
כסף משנה
18.
When the father heard the vow and nullified it and then died and then the erus heard [of the vow] or even if the erus heard of the vow before the death of the father,58But did not nullify it then. she is not transferred [entirely] to the domain of her erus. He cannot ever nullify the vow after the father's death, for an erus can nullify a vow only together [with the father].

הלכה יט
שָׁמַע אָרוּס וְהֵפֵר לָהּ וּמֵת וְאַחַר כָּךְ שָׁמַע הָאָב. אוֹ שֶׁשָּׁמַע הָאָב וְהֵפֵר לָהּ וּמֵת הַבַּעַל קֹדֶם שֶׁיִּשְׁמַע. אֵין הָאָב לְבַדּוֹ יָכוֹל לְהָפֵר נְדָרִים אֵלּוּ שֶׁנִּרְאוּ לְאָרוּס רִאשׁוֹן אֶלָּא בְּשֻׁתָּפוּת אָרוּס הָאַחֲרוֹן אִם נִתְאָרְסָה בּוֹ בַּיּוֹם כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
19.
If the erus heard [the vow], nullified it, and died and then the father heard or the father heard and nullified it and the erus died before he heard it, the father cannot nullify these vows that were in the jurisdiction of the first erus except together with a second erus to whom she is consecrated that day,59If, however, he nullifies on a later date it is unacceptable, for the father must nullify the vow on the day he became aware of it. as we explained.60Halachah 15. In his gloss to this halachah, the Radbaz explains the apparent contradiction between this halachah and Halachah 16 by stating that Halachah 16 refers to an instance where the father did not nullify the vow before the erus died. Accordingly, the right of the erus to nullify the vow is not weakened. Hence it can be transferred to the father. This halachah refers to a situation where the father nullified the vow and weakens it. Hence it cannot be transferred as explained in the notes to Halachah 15. This understanding is reflected in the ruling of the Shulchan Aruch (Yoreh De'ah 234:16).

הלכה כ
נָדְרָה וְהֵפֵר לָהּ אָבִיהָ לְבַדּוֹ וְלֹא שָׁמַע הָאָרוּס עַד שֶׁנִּכְנְסָה לִרְשׁוּתוֹ אֵינוֹ יָכוֹל לְהָפֵר שֶׁאֵין הַבַּעַל מֵפֵר נִדְרֵי אֲרוּסָתוֹ אַחַר שֶׁנִּשֵּׂאת אֶלָּא קֹדֶם שֶׁתִּכָּנֵס לִרְשׁוּתוֹ הוּא שֶׁמֵּפֵר בְּשֻׁתָּפוּת הָאָב. לְפִיכָךְ הָיָה דֶּרֶךְ תַּלְמִידֵי חֲכָמִים עַד שֶׁלֹּא תֵּצֵא בִּתּוֹ מֵרְשׁוּתוֹ אוֹמֵר לָהּ כָּל נְדָרִים שֶׁנָּדַרְתְּ בְּתוֹךְ בֵּיתִי הֲרֵי הֵן מוּפָרִין:
כסף משנה
20.
If a woman took a vow, her father nullified it alone, and her husband did not hear [of the vow] until he brought her into his domain,61I.e., completed the second stage of the marriage, nissuin. he cannot nullify [her vow]. For a husband cannot nullify a vow taken by the woman he consecrated after he marries her.62See Halachah 8. Instead, [this must be done] before she enters his domain, when he nullifies it together with her father. For this reason,63I.e., to enable all the vows concerning which he did not hear to be nullified. it was the practice of Torah Sages to tell their daughters before they left their domain:64I.e., before their marriage. "All the vows which you took while in my household are nullified."

הלכה כא
וְכֵן הַבַּעַל עַד שֶׁלֹּא תִּכָּנֵס לִרְשׁוּתוֹ אוֹמֵר לָהּ כָּל נְדָרִים שֶׁנָּדַרְתְּ מִשֶּׁאֵרַסְתִּיךְ עַד שֶׁלֹּא תִּכָּנְסִי בְּתוֹךְ בֵּיתִי הֲרֵי הֵן מוּפָרִין שֶׁהַבַּעַל מֵפֵר נִדְרֵי אִשְׁתּוֹ אַף עַל פִּי שֶׁלֹּא שָׁמַע אוֹתָם:
כסף משנה
21.
Similarly, the husband would tell her before she enters his domain: "All of the vows that you took from the time I consecrated you65An erus may also nullify the vows that a woman took before he consecrated her (together with her father). We assume, however, that her father already nullified those vows (Siftei Cohen 234:21; Turei Zahav 234:11). until you entered my home are nullified." For a husband66This also applies to her father. The husband and the father must, however, be capable of hearing. If they are deaf, they cannot nullify a vow (Chapter 12, Halachah 13). can nullify the vows of his wife even though he did not hear them.67Thus if both the father and the husband made these statements, the vows are nullified. In some manuscript copies of the Mishneh Torah, these two halachot are combined as one.

הלכה כב
הָלַךְ הָאָב עִם שְׁלוּחֵי הַבַּעַל אוֹ שֶׁהָלְכוּ שְׁלוּחֵי הָאָב עִם שְׁלוּחֵי הַבַּעַל עֲדַיִן אָבִיהָ וּבַעְלָהּ מְפֵרִין נְדָרֶיהָ. מָסַר הָאָב לִשְׁלוּחֵי הַבַּעַל אוֹ שֶׁמָּסְרוּ שְׁלוּחֵי הָאָב לִשְׁלוּחֵי הַבַּעַל אֵין הָאָב יָכוֹל לְהָפֵר שֶׁהֲרֵי יָצָאת מֵרְשׁוּתוֹ וְלֹא הַבַּעַל יָכוֹל לְהָפֵר שֶׁאֵין הַבַּעַל מֵפֵר בְּקוֹדְמִין כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
22.
If the father went with the agents of the husband68Who were sent to bring her to her husband's home. or the father's agents went with the agents of the husband, her vows must still be nullified by her father and her husband jointly.69As long as her father is accompanying her, he is not considered to have transferred her to her husband's domain and hence, still has the right to nullify her vows. If her father transferred her to the agents of her husband or her father's agents transferred her to her husband's agents, her father can no longer nullify her vows.70I.e., even if the husband dies [Shulchan Aruch (Yoreh De'ah 234:12)]. Nor may the husband nullify them. For the husband cannot nullify vows that were taken before [he married her], as we explained.71See Halachah 20.

הלכה כג
שׁוֹמֶרֶת יָבָם אֲפִלּוּ עָשָׂה בָּהּ יְבָמָהּ מַאֲמָר וַאֲפִלּוּ יָבָם אֶחָד לִיבָמָה אַחַת אֵינוֹ מֵפֵר נִדְרֵי יְבִמְתּוֹ עַד שֶׁיָּבוֹא עָלֶיהָ:
כסף משנה
23.
When a woman is waiting for yivum72I.e., we are speaking about a widow whose husband dies childless who must be married by her deceased husband's brother. See Deuteronomy, ch. 25. - even if the yevam already made a statement of his intent,73Which is similar to consecration, but not entirely analogous to consecration (see Hilchot Yibbum ViChalitzah 2:1). and even if there is only one yevam and one yevamah74And thus there is no question that she is designated for him. - [the yevam] may not nullify her vows until he is intimate with her.75At which point their marriage is consummated and she becomes his wife. Until then, even if he has stated his intent, according to Scriptural Law, she is not his wife and he cannot nullify her vows.

הלכה כד
הָיְתָה יְבִמְתּוֹ נַעֲרָה מְאֹרָסָה לְאָחִיו וְאָבִיהָ קַיָּם אֵין הַיָּבָם וְאָבִיהָ מְפֵרִים נְדָרֶיהָ כְּאַחַת אֶלָּא הָאָב לְבַדּוֹ הוּא שֶׁמֵּפֵר כָּל שֶׁתִּדֹּר וַאֲפִלּוּ עָשָׂה בָּהּ הַיָּבָם מַאֲמָר אֵינָהּ כְּנַעֲרָה מְאֹרָסָה. שֶׁאֵין הַמַּאֲמָר קוֹנֶה בִּיבָמָה קִנְיָן גָּמוּר כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
24.
When a yevamah who is a maiden had been [merely] consecrated to [her deceased husband] and her father is alive, the yevam and her father do not nullify her vows together. Instead, her father alone is the one who nullifies any vow that she takes.76As stated in Halachah 10. Even if the yevam stated his intent to marry her, she is not considered as a consecrated maiden, for a statement of intent does not [establish] a complete [marriage bond between] a yevamah [and her yevam], as we explained.77Which is similar to consecration, but not entirely analogous to consecration (see Hilchot Yibbum ViChalitzah 2:1).

הלכה כה
נַעֲרָה שֶׁהִשִּׂיאָהּ אָבִיהָ וְנִתְאַלְמְנָה אוֹ נִתְגָּרְשָׁה מִן הַנִּשּׂוּאִין הֲרֵי זוֹ כִּיתוֹמָה בְּחַיֵּי הָאָב. וְאֵין אָבִיהָ מֵפֵר נְדָרֶיהָ וְאַף עַל פִּי שֶׁעֲדַיִן הִיא נַעֲרָה:
כסף משנה
25.
When a maiden who was given in marriage by her father is widowed or divorced after marriage,78I.e., she has already completed nissuin, the second stage of the marriage bond. she is like an orphan in her father's lifetime. Her father does not have the right to nullify her vows even if she is a maiden.79I.e., although from the standpoint of age, her father would still have the right to nullify her vows, since she married, she is given full independence. Hence, he no longer has this right.

הלכה כו
נַעֲרָה מְאֹרָסָה שֶׁנָּדְרָה וְלֹא שָׁמְעוּ נְדָרֶיהָ אָבִיהָ וּבַעְלָהּ עַד שֶׁבָּגְרָה אוֹ עַד שֶׁנַּעֲשֵׂית יְתוֹמָה בְּחַיֵּי הָאָב הֲרֵי נְדָרֶיהָ קַיָּמִים וְאֵין הַבַּעַל יָכוֹל לְהָפֵר שֶׁהֲרֵי יָצָאת מֵרְשׁוּת אָבִיהָ שֶׁהוּא מֵפֵר עִמּוֹ בְּשֻׁתָּפוּת וַעֲדַיִן לֹא נִכְנְסָה לִרְשׁוּת הַבַּעַל:
כסף משנה
26.
When a consecrated maiden takes a vow, but neither her father or her husband heard of her vows until she came of age80As stated in Halachah 7, once she comes of age, her father no longer has any authority over her. or until she became like an orphan in her father's lifetime,81I.e., she was divorced or widowed after marriage, as stated in the previous halachah. her vows are binding; they cannot be nullified by her erus.82I.e., in the first situation, the man who consecrated her before she came of age. In the second situation, it refers to a second husband who consecrated her after she was divorced or widowed. [The rationale is that] she departed from her father's domain and he [and her erus] must nullify her vows together and she has not entered her husband's domain.83This occurs only after nissuin. Moreover, even after she enters her husband's domain, he cannot nullify her vows that were taken beforehand, as stated in Halachah 20.

הפלאה הלכות נדרים פרק יא
Haflaah Nedarim Chapter 11