Halacha

הלכה א
הָאִשָׁה שֶׁהִתְנֵית עַל בַּעְלָהּ לְבַטֵּל זְכוּת מִדְּבָרִים שֶׁזּוֹכֶה בָּהֶן הַבַּעַל אִם כָּתַב לָהּ וְעוֹדָהּ אֲרוּסָה קֹדֶם הַנִּשּׂוּאִין אֵינוֹ צָרִיךְ לִקְנוֹת מִיָּדוֹ. אֶלָּא כָּל מַה שֶּׁכָּתַב לָהּ קַיָּם. וְאִם כָּתַב לָהּ אַחַר הַנִּשּׂוּאִין צָרִיךְ לִקְנוֹת מִיָּדוֹ:
כסף משנה
1.
[The following rules apply when] a woman makes a provision with her husband in which he agrees to forgo one of the privileges that a husband is granted. If he wrote down [this provision] for her after she was consecrated, but before nisu'in, there is no need to formalize the matter with an act of contract; everything he wrote to her is binding.1Since the man has already established a connection with this woman, but has not acquired the rights due him by virtue of the ketubah, any provision that he makes regarding those rights is binding. If he wrote down [this provision] for her after nisu'in, he must formalize the matter with an act of contract.2Since the bond of marriage has already been consummated, the husband has already acquired all the rights to which he is entitled. Therefore, a verbal statement is not sufficient, and an official act of contract is necessary to forgo those rights. (See Ketubot 83a, which compares this to the absolution of a partnership agreement.)

הלכה ב
הִתְנָה עִמָּהּ שֶׁלֹּא יִהְיוּ לוֹ דִּין וּדְבָרִים בִּנְכָסֶיהָ אִם מָכְרָה וְנָתְנָה מִכְרָהּ וּמַתְּנָתָהּ קַיָּם. אֲבָל אוֹכֵל פֵּרוֹתֵיהֶן כָּל זְמַן שֶׁהֵן בִּרְשׁוּתָהּ. וְאִם קָנוּ מִיָּדוֹ כְּשֶׁהִיא אֲרוּסָה שֶׁאֵין לוֹ דִּין וּדְבָרִים בִּנְכָסֶיהָ הֲרֵי סִלֵּק עַצְמוֹ מִגּוּף הַקַּרְקַע וְאֵין לוֹ בִּנְכָסֶיהָ פֵּרוֹת לְעוֹלָם. וַאֲפִלּוּ עִרְעֵר עַל קִנְיָנוֹ וְאָמַר לֹא עָלָה בְּדַעְתִּי שֶׁאֵין לִי פֵּרוֹת מִפְּנֵי קִנְיָן זֶה אֶלָּא שֶׁאִם מָכְרָה מִכְרָהּ קַיָּם שֶׁאֵין אָדָם נוֹשֵׂא אִשָּׁה בְּלֹא נְכָסִים אֵין שׁוֹמְעִין לוֹ אֶלָּא כְּבָר סִלֵּק עַצְמוֹ מִגּוּף הַקַּרְקַע:
כסף משנה
2.
If, [after nisu'in,] the husband stipulates that he will have no say with regard to [his wife's] property, and she sells it or gives it away as a present, the sale or the present is binding.3Moreover, the husband is not entitled to any benefit that accrues from the money his wife receives from the sale (Ramah, Even HaEzer 92:1). Nevertheless, [the husband] is entitled to the benefits [that accrue from the property] during the time it is in her possession.4A husband has three rights with regard to his wife's property: to receive the benefits that accrue from it, to veto any sales or presents, and to inherit it in the event of his wife's death. Since the wording of the provision in the document the husband gave his wife is not specific, he is given the benefit of the doubt and is considered to have waived the least valuable of the rights he has: the veto power over his wife's sales and gifts (Rashi, Ketubot 83b).
If he affirmed these statements with an act of contract between consecration [and nisu'in], he is considered to have waived his rights to the land itself, and he no longer has any rights to the benefits that accrue from her property.5The rationale is that before nisu'in, a deed of contract is not necessary to uphold any sale or gift that a woman may make. Since the husband took an additional step and carried out an act of contract, we assume that he did so with the intent of enhancing his wife's position and waiving all rights he has to her property (Kessef Mishneh).
This is the Rambam's interpretation of the above passage. The Ra'avad and Rabbenu Asher advance a different interpretation. The Shulchan Aruch (Even HaEzer 92:3) quotes both opinions, but appears to favor that of the Rambam.

His words are not heeded if he protests this action, saying: "I did not realize that this act of contract formalized my waiver of all rights to benefit from the property. [I thought that it only entitled my wife] to make a binding sale. [This interpretation is justified,] for no one will marry a woman without property." Instead, he is considered to have waived [all] rights to the land itself.

הלכה ג
הִתְנָה עִמָּהּ שֶׁלֹּא יֹאכַל פֵּרוֹת נְכָסֶיהָ הֲרֵי זֶה אֵינוֹ אוֹכֵל פֵּרוֹתֵיהֶן אֲבָל מוֹכְרִין אֶת הַפֵּרוֹת וְלוֹקְחִין בָּהֶן קַרְקַע וְהוּא אוֹכֵל פֵּרוֹתֶיהָ. שֶׁלֹּא סִלֵּק עַצְמוֹ אֶלָּא מִפֵּרוֹת נְכָסִים אֵלּוּ בִּלְבַד:
כסף משנה
3.
If [the husband] made a provision with [his wife] not to receive the benefit that accrues from her property, he is not entitled to this benefit. Nevertheless, the benefit that accrues should be converted to financial resources, landed property should be purchased, and [the husband] is entitled to the benefits from that property.6From the Rambam's wording, it appears that it is imperative that the benefits from the land be converted into financial resources and be used to purchase other property. Rabbenu Asher and others do not accept this position and maintain that the woman has the right to use the benefits that accrue from the land as she desires. If, however, she decides to use them to purchase property, her husband is entitled to the benefits that accrue from that property. The Shulchan Aruch (Even HaEzer 94:4) quotes the Rambam's view, while the Ramah follows that of Rabbenu Asher. For he waived only the rights to the property [she owned originally].

הלכה ד
הִתְנָה עִמָּהּ שֶׁלֹּא יֹאכַל פֵּרוֹת נְכָסֶיהָ וְלֹא פֵּירֵי פֵּרוֹתֵיהֶן לוֹקְחִין הַפֵּרוֹת וְקוֹנִין בָּהֶם קַרְקַע וְלוֹקְחִין פֵּרוֹת קַרְקַע זוֹ וְקוֹנִין בָּהֶם קַרְקַע שְׁנִיָּה וְהוּא אוֹכֵל פֵּרוֹת אֵלּוּ שֶׁהֵן פֵּירֵי פֵּירֵי פֵּרוֹת. וְכֵן הַדָּבָר תָּמִיד עַד שֶׁיַּתְנֶה עִמָּהּ שֶׁלֹּא יִהְיוּ לוֹ לֹא פֵּרוֹת וְלֹא פֵּירֵי פֵּרוֹתֵיהֶן עַד לְעוֹלָם. וְאַחַר כָּךְ לֹא יִהְיוּ לוֹ פֵּרוֹת בְּחַיֶּיהָ אֲבָל אִם מֵתָה יִירַשׁ הַכּל:
כסף משנה
4.
If [the husband] made a provision with [his wife] not to receive the benefit that accrues from her property, nor to receive the benefit that results from property purchased with the income from her original property, the proceeds from that property should be used to purchase other property, from which [the husband] is entitled to the benefits that accrue. These are called "the fruit of the fruit's fruit."
This pattern continues until the husband makes a provision that he has no right to any by-product of the proceeds from [his wife's property]. [If he makes such a provision,] he has no right to any benefit during her lifetime, but if she dies, he inherits her entire estate.

הלכה ה
הִתְנָה עִמָּהּ שֶׁלֹּא יִירָשֶׁנָּה הֲרֵי זֶה לֹא יִירָשֶׁנָּה אֲבָל אוֹכֵל פֵּרוֹת בְּחַיֶּיהָ. וְכֵן אִם הִתְנָה עִמָּהּ שֶׁיִּירַשׁ מִקְצָת נְכָסִים וְכֵן אִם הִתְנָה עִמָּהּ שֶׁאִם מֵתָה בְּלֹא בָּנִים יַחְזְרוּ נְכָסִין לְבֵית אָבִיהָ הַכּל קַיָּם:
כסף משנה
5.
If he makes a provision that he will not inherit [his wife's] property, the provision is binding. He is, however, entitled to receive the benefits that accrue [from this property] during her lifetime.
Similarly, [his word] is binding if he stipulates that he will inherit [only] a portion of her estate, or if he stipulates that if she dies without bearing children, her estate will return to her father's household.

הלכה ו
בַּמֶּה דְּבָרִים אֲמוּרִים שֶׁהִתְנָה עִמָּהּ קֹדֶם שֶׁתִּנָּשֵׂא שֶׁהַנַּחֲלָה הַבָּאָה לוֹ לָאָדָם שֶׁלֹּא מִמִּשְׁפַּחְתּוֹ מַתְנֶה עָלֶיהָ שֶׁלֹּא יִירָשֶׁנָּה קֹדֶם שֶׁתְּהֵא רְאוּיָה לוֹ. אֲבָל אִם הִתְנָה עִמָּהּ אַחַר שֶׁנִּשֵּׂאת תְּנָאוֹ בָּטֵל וְיִירָשֶׁנָּה כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
6.
When does the above apply? When he made this provision before nisu'in.7If, however, the provision is made before the woman is consecrated, it is also of no consequence. For until a connection between the man and the woman is established, his statements regarding her property are of no consequence whatsoever. For a man has the prerogative to forgo an inheritance that comes to him from a source outside his family before he acquires the rights to it. If, however, he made the provision after nisu'in, his provision is not binding, and he inherits her estate as we explained.8See Chapter 12, Halachah 9.

הלכה ז
הִתְנָה עִמָּהּ אַחַר נִשּׂוּאִין שֶׁלֹּא יִהְיוּ לוֹ דִּין וּדְבָרִים בִּנְכָסֶיהָ וְלֹא בְּפֵירֵי פֵּרוֹתֶיהָ עַד עוֹלָם בְּחַיֶּיהָ וּבְמוֹתָהּ הֲרֵי זֶה אֵינוֹ אוֹכֵל פֵּרוֹת כְּלָל. אֲבָל אִם מֵתָה יִירָשֶׁנָּה כְּמוֹ שֶׁבֵּאַרְנוּ:
כסף משנה
7.
When, after nisu'in, [a husband] stipulates9And affirms his provision with an act of contract (Maggid Mishneh). that he has no say with regard to his wife's property - not with regard to the benefits from that property nor any eventual byproducts from them during her lifetime - then after her death he is not entitled to any benefit from this property at all.10Nor does he have the right to veto a sale (Chelkat Mechokek 92:17). If she dies, however, he inherits her estate, as explained [above].

הלכה ח
הַבַּעַל שֶׁהוֹצִיא הוֹצָאוֹת עַל נִכְסֵי מְלוֹג בֵּין שֶׁהוֹצִיא מְעַט וְאָכַל פֵּרוֹת הַרְבֵּה בֵּין שֶׁהוֹצִיא הַרְבֵּה וְאָכַל פֵּרוֹת מְעַט וַאֲפִלּוּ אָכַל גְּרוֹגֶרֶת אַחַת דֶּרֶךְ כָּבוֹד אוֹ שֶׁאָכַל דִּינָר אֶחָד אֲפִלּוּ שֶׁלֹּא דֶּרֶךְ כָּבוֹד וַאֲפִלּוּ לֹא לָקַח בַּפֵּרוֹת מִמַּה שֶּׁהוֹצִיא אֶלָּא חֲבִילָה אַחַת שֶׁל זְמוֹרוֹת. מַה שֶּׁהוֹצִיא הוֹצִיא וּמַה שֶּׁאָכַל אָכַל:
כסף משנה
8.
[The following rules apply] when a husband spends money [to improve property belonging to his wife that is classified as] nichsei m'log. Whether he spent a small amount and derived much benefit, or spent a large amount and derived little benefit [he is not required to pay anything, nor may he collect anything]; what he spent, he spent, and the benefit that he enjoyed, he enjoyed.
[The above applies] even if he ate only one dried fig in a respectful manner,11I.e., at home, on his table. if he ate a dinar's worth of produce in a haphazard manner, or if he did not even take produce [from the field on which he spent money] and took merely a bundle of twigs.12This bundle must be worth at least a dinar (Chelkat Mechokek 88:12).

הלכה ט
וְכֵן אִם נָפְלוּ לָהּ כְּסָפִים בְּמָקוֹם רָחוֹק וְהוֹצִיא עֲלֵיהֶן הוֹצָאוֹת עַד שֶׁהֱבִיאָן אוֹ עַד שֶׁהוֹצִיאָן מִיַּד מִי שֶׁהָיוּ אֶצְלוֹ וְלָקַח בָּהֶן קַרְקַע וְאָכַל פֵּרוֹתֶיהָ כַּשִּׁעוּר מַה שֶּׁהוֹצִיא הוֹצִיא וּמַה שֶּׁאָכַל אָכַל. הוֹצִיא וְלֹא אָכַל אוֹ שֶׁאָכַל פָּחוֹת מִכַּשִּׁעוּר שָׁמִין כַּמָּה שֶׁהִשְׁבִּיחוּ וְשׁוֹאֲלִין אוֹתוֹ כַּמָּה הוֹצִיא. אִם הַשֶּׁבַח יֶתֶר עַל הַהוֹצָאָה יִשָּׁבַע בִּנְקִיטַת חֵפֶץ כַּמָּה הוֹצִיא וְנוֹטֵל הַהוֹצָאָה. וְאִם הַהוֹצָאָה יְתֵרָה עַל הַשֶּׁבַח אֵין לוֹ מִן הַהוֹצָאָה אֶלָּא כְּשִׁעוּר הַשֶּׁבַח וּבִשְׁבוּעָה:
כסף משנה
9.
Similar [laws apply] if a woman inherited funds in a distant place, and the husband undertook expenses in order to bring them [to their home], or [expenses were required] to take them from the person who was holding them. If [the husband] purchased land [with these funds] and ate the measure of fruit [mentioned above, he is not required to pay anything, nor may he collect anything]; what he spent, he spent, and the benefit that he enjoyed, he enjoyed.
[The following procedure is adhered to if] a husband incurred expenses [on behalf of his wife's property] and did not derive any benefit or derived less benefit than the above measure. We evaluate the increment to the property, and we ask him the extent of his expenses.
If the increment is greater than the expenses, the husband must take an oath holding a sacred object, stating how much he spent. He is then reimbursed for those expenses.13If the wife denies his claim and states that she is sure that he spent less, her claim is accepted provided she supports it with an oath (Ramah, Even HaEzer 88:7, Beit Shmuel 88:17). If the increment is less than the expenses, he receives only the amount of the expenses that is justified by the increment, and he must take an oath [with regard to the extent of those expenses].

הלכה י
בַּמֶּה דְּבָרִים אֲמוּרִים בִּמְגָרֵשׁ אֲבָל הָאִשָּׁה שֶׁמָּרְדָה עַל בַּעְלָהּ אֲפִלּוּ אָכַל הַרְבֵּה שָׁמִין לוֹ כַּמָּה אָכַל וּפוֹחֵת אוֹתוֹ מִמַּה שֶּׁרָאוּי לִתֵּן לוֹ מִן הַהוֹצָאָה אַחַר שֶׁיִּשָּׁבַע וְנוֹטְלוֹ. שֶׁלֹּא הִקְנָה לָהּ כְּדֵי שֶׁתִּטּל וְתֵצֵא מֵעַצְמָהּ. וְכֵן הַמּוֹצִיא הוֹצָאוֹת עַל נִכְסֵי אִשְׁתּוֹ קְטַנָּה וּמֵאֲנָה בּוֹ רוֹאִין כַּמָּה אָכַל וְכַמָּה הוֹצִיא וְכַמָּה הִשְׁבִּיחַ וְשָׁמִין לוֹ כְּאָרִיס שֶׁהֲרֵי בִּרְשׁוּת יָרַד:
כסף משנה
10.
When does the above apply? When a husband divorces his wife [under ordinary circumstances]. [Different rules apply regarding] a woman who rebels against her husband [and denies him intimacy].14See Chapter 14, Halachah 8. Even if he derived much benefit, the benefit that he derives should be evaluated and subtracted from the amount fit to be given him for the expenses he undertook.15As reflected by the Rambam's Commentary on the Mishnah (Ketubot 8:6), this applies only when the increment to the property exceeds the expenses. If the expenses exceed the increment, all he receives is the increment. (See Beit Shmuel 88:18, who quotes other authorities who differ.) After he takes an oath [affirming his claim], he is entitled to collect it. For he did not [incur these expenses on behalf of his wife] so that she would take them and leave him on her own accord.
Similarly, [different rules apply when] a man undertakes expenses [to develop] property belonging to his wife who is below the age of majority, and she dissolves the marriage through the right of mi'un.16See Chapter 4, Halachah 8. We evaluate the amount of benefit he received, the amount of his expenses, the extent of the property's increment - and then he is given the share usually allocated to a sharecropper.17If the husband were not given consideration for his expenses and the increment he brought to the woman's property, he would seek only his own benefit and would deplete the property's value by failing to fertilize it and constantly sowing crops. This is unlikely to happen if he is given a sharecropper's allocation. In such an instance, he is likely to say: "It is possible that the marriage will continue, and so it is to my benefit to maintain the field's value. Even if the marriage does not continue, I will be justly reimbursed for my work."[This consideration is taken] because he had permission to work [his wife's property].18The Shulchan Aruch (Even HaEzer 88:10) explains that the option is the husband's. He may choose to receive a sharecropper's allocation, or he may desire to leave the property without making a reckoning, as is done in the case when his wife is past the age of majority.

הלכה יא
מִנְהָגוֹת רַבּוֹת יֵשׁ בִּנְדוּנְיָא. יֵשׁ מְקוֹמוֹת שֶׁנָּהֲגוּ שֶׁיִּכְתְּבוּ בַּכְּתֻבּוֹת הַנְּדוּנְיָא יֶתֶר עַל דָּמֶיהָ בִּשְׁלִישׁ אוֹ בְּחֹמֶשׁ אוֹ בְּמֶחֱצָה. כְּגוֹן שֶׁתִּהְיֶה הַנְּדוּנְיָא מֵאָה וְכוֹתְבִים שֶׁהִכְנִיסָה מֵאָה וַחֲמִשִּׁים כְּדֵי לְהַרְבּוֹת בִּפְנֵי הָעָם וּכְשֶׁתָּבוֹא לִגְבּוֹת לֹא תִּגְבֶּה אֶלָּא הַמֵּאָה. וְיֵשׁ מְקוֹמוֹת שֶׁנָּהֲגוּ לִכְתֹּב פָּחוֹת. וְאִם פָּסְקָה לְהָבִיא לוֹ בְּמֵאָה כֵּלִים נוֹתֶנֶת שְׁוֵה מֵאָה וְעֶשְׂרִים אוֹ מֵאָה וַחֲמִשִּׁים וְכוֹתְבִין שֶׁהִכְנִיסָה לוֹ מֵאָה. וְיֵשׁ מְקוֹמוֹת שֶׁנָּהֲגוּ לִכְתֹּב שְׁוֵה מָנֶה בְּמָנֶה. וְיֵשׁ מְקוֹמוֹת שֶׁנָּהֲגוּ שֶׁיִּתֵּן הָאִישׁ מָעוֹת לְפִי הַנְּדוּנְיָא דָּבָר קָצוּב שֶׁתִּתְקַשֵּׁט בּוֹ הַכַּלָּה וְתִקְנֶה בּוֹ בְּשָׂמִים וְכַיּוֹצֵא בָּהֶן. וְיֵשׁ מְקוֹמוֹת שֶׁיַּכְנִיס הָאִישׁ שׁוּם מִשֶּׁלּוֹ לָאִשָּׁה וְיִצְטָרֵף לִנְדֻנְיָתָהּ לְהִתְנָאוֹת בּוֹ:
כסף משנה
11.
There are various customs regarding [a woman's] dowry. In certain places it is customary to [state a higher figure] in the ketubah [with regard to the value of the dowry], increasing by a third, a fifth or a half. For example, if the dowry was 100 [zuz], it is written [in the ketubah] that the woman brought 150 [to the household], in order to appear more generous in the eyes of the people. [Therefore,] when the woman comes to collect her dowry, she collects only 100.
Conversely, there are places where it is customary to write a lesser amount. If it is agreed that she will bring utensils worth 100 [zuz to the household], she must bring a value of 120 or 150, and yet, [in the ketubah,] it is written that she brought only [a value of] 100.19In this instance, the woman collects the greater sum when she collects her due. And there are other places where it is customary to write a value of 100 [zuz] as 100.
There are places where it is customary for a man to give a set amount of money proportionate to the dowry, for the bride to adorn herself and purchase perfume and the like. There are places where [it is customary for] the man to add an additional sum of his own for his wife and add it to her dowry, for her to appear attractive.

הלכה יב
הַנּוֹשֵׂא סְתָם כּוֹתֵב וְנוֹתֵן כְּמִנְהַג הַמְּדִינָה. וְכֵן הִיא שֶׁפָּסְקָה לְהַכְנִיס נוֹתֶנֶת כְּמִנְהַג הַמְּדִינָה וּכְשֶׁתָּבֹא לִגְבּוֹת כְּתֻבָּתָהּ מַגְבִּין לָהּ מַה שֶּׁבִּכְתֻבָּתָהּ כְּמִנְהַג הַמְּדִינָה. וּבְכָל הַדְּבָרִים הָאֵלּוּ וְכַיּוֹצֵא בָּהֶן מִנְהַג הַמְּדִינָה עִקָּר גָּדוֹל הוּא וְעַל פִּיו דָּנִין וְהוּא שֶׁיִּהְיֶה אוֹתוֹ מִנְהָג פָּשׁוּט בְּכָל הַמְּדִינָה:
כסף משנה
12.
When a man marries a woman without specifying any conditions, he should write her a ketubah, giving her a sum that is customarily given in that locale. Similarly, if she makes a commitment to bring [utensils to the household], she must bring what is customarily brought in that locale. And when she comes to collect [the money due her by virtue of] her ketubah, she collects as is customary in that locale.
In this and in all similar matters, local custom is a fundamental principle, and it is used as a basis for judgment, provided that the custom is commonly accepted in the locale.

הלכה יג
אִישׁ וְאִשָּׁה שֶׁהָיוּ בֵּינֵיהֶם שִׁדּוּכִין וְאָמַר לָהּ כַּמָּה אֶת מַכְנֶסֶת לִי כָּךְ וְכָךְ וְאָמְרָה לוֹ וְכַמָּה אַתָּה נוֹתֵן לִי אוֹ כּוֹתֵב לִי כָּךְ וְכָךְ. וְכֵן הָאָב שֶׁפָּסַק עַל יְדֵי בְּנוֹ וּבִתּוֹ כַּמָּה אַתָּה נוֹתֵן לְבִנְךָ כָּךְ וְכָךְ וְכַמָּה אַתָּה נוֹתֵן לְבִתְּךָ כָּךְ וְכָךְ וְעָמְדוּ וְקִדְּשׁוּ קָנוּ אוֹתָן הַדְּבָרִים וְאַף עַל פִּי שֶׁלֹּא הָיָה בֵּינֵיהֶן קִנְיָן. וְאֵלּוּ הֵן הַדְּבָרִים הַנִּקְנִים בַּאֲמִירָה:
כסף משנה
13.
[The following rules apply when a man and a woman were engaged to each other. When he asks her, "What is the value [of the utensils] you are bringing [to the household]?", and she answers him with an amount, and she asks him, "How much will you give me [for my ketubah]?", and he answers with an amount, and afterwards he arises and consecrates her, the commitments are binding even though they were not formalized with an act of contract.20In Hilchot Zechiyah UMatanah 6:17, the Rambam adds several dimensions to this statement: a) The person making the commitment must own the items he promises. If he does not own them, his commitment is not binding, for a person cannot transfer an entity that does not yet exist.
b) The commitment is not binding on property that has been sold. For only transactions that are formalized by a written deed are binding on the purchasers of property. Moreover, since this commitment can be formalized by the spoken word alone, even if it is later recorded in a written document, it is not binding on the purchasers. If, however, a formal deed of transfer is composed, it must be honored by the purchasers (Maggid Mishneh, Hilchot Zechiyah UMatanah). (See also Halachah 18.)
c) The transaction is not effective until the marriage takes place.

Similarly, a commitment made by a father on behalf of his son or daughter [is binding]. For example, if he is asked, "How much will you give on behalf of your son?", and he specifies an amount, or he is asked "How much will you give on behalf of your daughter?", and he specifies an amount, [his commitment is binding].
These are commitments that are established through speech alone.21In general, a business agreement must be formalized by a contractual act (a kinyan), and a verbal commitment is not sufficient. An exception is made in this instance because of the happiness and closeness engendered by the marriage relationship (Ketubot 102b).

הלכה יד
בַּמֶּה דְּבָרִים אֲמוּרִים בְּשֶׁפָּסַק הָאָב לְבִתּוֹ בֵּין קְטַנָּה וּבֵין גְּדוֹלָה וּפָסַק הָאָב לִבְנוֹ [ב.] וּבְנִשּׂוּאִין רִאשׁוֹנִים שֶׁדַּעְתּוֹ שֶׁל אָדָם קְרוֹבָה אֵצֶל בְּנוֹ וּמֵרֹב שִׂמְחָתוֹ בַּנִּשּׂוּאִין הָרִאשׁוֹנִים גָּמַר וּמַקְנֶה לוֹ בַּאֲמִירָה. אֲבָל אָח שֶׁפָּסַק לַאֲחוֹתוֹ אוֹ אִשָּׁה שֶׁפָּסְקָה לְבִתָּהּ וְכֵן שְׁאָר קְרוֹבִים וְכֵן הָאָב שֶׁפָּסַק לִבְנוֹ אוֹ לְבִתּוֹ בְּנִשּׂוּאִין שְׁנִיִּים לֹא קָנוּ אוֹתָן הַדְּבָרִים עַד שֶׁיִּקְנוּ מִידֵי הַפּוֹסֵק שֶׁיִּתֵּן כָּךְ וְכָךְ:
כסף משנה
14.
When does the above apply? When a father made a commitment on behalf of his daughter, whether she is a minor or past majority, or on behalf of his son, for their first marriage. For a man feels an inner connection to his son, and because of his happiness at his first marriage, he makes a definite commitment, and designates [the sum] for him with a verbal statement [alone].
[Different rules apply when], by contrast, a brother makes a commitment on behalf of his sister, a woman makes a commitment on behalf of her daughter, [when a commitment is made by] other relatives, and similarly, when a father makes a commitment on behalf of his son or daughter for a second marriage.22If, by contrast, a man or a woman makes a commitment for his or her own marriage, the commitment is binding without a contractual act, even if it is a second marriage that is involved. The commitment is not binding until the person making it formalizes it with an act of contract and states the amount he will give.

הלכה טו
הָאָב שֶׁפָּסַק עַל יַד בִּתּוֹ לֹא קָנְתָה הַבַּת אוֹתָהּ הַמַּתָּנָה עַד שֶׁיִּכְנֹס אוֹתָהּ בַּעְלָהּ. וְכֵן הַבֵּן לֹא קָנָה עַד שֶׁיִּכְנֹס. שֶׁכָּל הַפּוֹסֵק אֵינוֹ פּוֹסֵק אֶלָּא עַל מְנָת לִכְנֹס. לְפִיכָךְ הַפּוֹסֵק מָעוֹת לַחֲתָנוֹ וּמֵת קֹדֶם שֶׁיִּכְנֹס וְנָפְלָה לִפְנֵי אָחִיו לְיִבּוּם יָכוֹל הָאָב לוֹמַר לַיָּבָם לְאָחִיךָ הָיִיתִי רוֹצֶה לִתֵּן וּלְךָ אֵינִי רוֹצֶה לִתֵּן. וַאֲפִלּוּ הָיָה הָרִאשׁוֹן עַם הָאָרֶץ וְהַשֵּׁנִי חָכָם. וְאַף עַל פִּי שֶׁהַבַּת רוֹצָה בּוֹ:
כסף משנה
15.
When a father makes a commitment for his daughter, the daughter does not acquire that present until her husband consummates the marriage with her.23I.e., nisu'in, the second stage of marriage, as well as erusin, the first stage, must be completed before the present is binding. Similarly, a son does not acquire [the present that he was promised] until he consummates his marriage. For whenever one makes [such] a commitment, his intent is that [it be fulfilled when] the marriage is consummated.
Therefore, when a man makes a commitment to his [prospective] son-in-law, but the son-in-law dies [after erusin, but] before the marriage is consummated, and the woman is bound to his brother, [if he desires to perform the rite of] yibbum, [the woman's] father may [retract his commitment], saying: "I desired to give your brother; I do not desire to give you." [This applies] even if the first husband was an unlearned man and the second is a Torah scholar, and even if the woman desires [to marry] the second man.24For it is her father who is making the financial commitment, not she.

הלכה טז
הַפּוֹסֵק מָעוֹת לַחֲתָנוֹ וְהָלַךְ הָאָב לִמְדִינָה אַחֶרֶת יְכוֹלָה הִיא לוֹמַר לַבַּעַל אֲנִי לֹא פָּסַקְתִּי עַל עַצְמִי מָה אֲנִי יְכוֹלָה לַעֲשׂוֹת אוֹ כְּנוֹס בְּלֹא נְדוּנְיָא אוֹ פָּטְרֵנִי בְּגֵט. אֲבָל אִם פָּסְקָה הִיא עַל עַצְמָהּ וְלֹא הִגִּיעָה יָדָהּ הֲרֵי זוֹ יוֹשֶׁבֶת עַד שֶׁתִּמְצָא מַה שֶּׁפָּסְקָה אוֹ עַד שֶׁתָּמוּת. וְלָמָּה לֹא תִּפְטֹר עַצְמָהּ בְּמַרְדּוּת. שֶׁהַמּוֹרֶדֶת וְהִיא אֲרוּסָה הַבַּעַל רוֹצֶה לְכָנְסָהּ וְהִיא אֵינָהּ רוֹצָה אֲבָל זוֹ אֵין הַבַּעַל רוֹצֶה בָּהּ עַד שֶׁתִּתֵּן הַנְּדוּנְיָא שֶׁפָּסְקָה וְהִיא רוֹצָה בּוֹ שֶׁהֲרֵי אוֹמֶרֶת לוֹ אוֹ כְּנֹס אוֹ פְּטֹר. בַּמֶּה דְּבָרִים אֲמוּרִים בִּגְדוֹלָה אֲבָל בִּקְטַנָּה שֶׁפָּסְקָה עַל עַצְמָהּ כּוֹפִין אוֹתוֹ לִתֵּן גֵּט אוֹ יִכְנֹס בְּלֹא נְדוּנְיָא:
כסף משנה
16.
When a man makes a financial commitment to his son-in-law and then moves to another country [without fulfilling his commitment], the woman has the prerogative of telling her [prospective] husband: "I did not make this commitment myself. What can I do? Either consummate the marriage without a dowry or divorce me."25I.e., the husband must take one of these two options. He cannot leave the woman consecrated (in which case she cannot marry someone else), but not married.
This ruling is quoted by the Shulchan Aruch (Even HaEzer 52:1). The Ramah states that if the woman has the financial means to meet the commitment, she must do so.

If, however, she made such a commitment herself, and she was not able to muster the funds, she must remain [in this intermediate state] until she accumulates the sum to which she committed herself or until she dies.
Why does she not release herself from her obligation by becoming a moredet26See Chapter 14, Halachot 8 and 12. against her husband? [Because there is a difference between these two instances.] With regard to a moredet who has [merely] been consecrated, the husband desires to consummate the marriage; it is she who does not desire. In this instance, by contrast, the husband does not want [to consummate his marriage with] her until she gives the dowry to which she committed herself. She, however, desires him, [as reflected by] her request: "Either consummate [the marriage] or divorce me."
When does the above apply? To a woman past majority. If, however, a woman makes a financial commitment while she is still a minor, we compel [her prospective husband] either to divorce her or to consummate the marriage without a dowry.

הלכה יז
הַנּוֹשֵׂא אִשָּׁה וּפָסְקָה עִמּוֹ שֶׁיִּהְיֶה זָן אֶת בִּתָּהּ כָּךְ וְכָךְ שָׁנִים חַיָּב לָזוּן אוֹתָם שָׁנִים שֶׁקִּבֵּל עַל עַצְמוֹ. וְהוּא שֶׁיַּתְנוּ עַל דָּבָר זֶה בִּשְׁעַת הַקִּדּוּשִׁין. אֲבָל שֶׁלֹּא בִּשְׁעַת הַקִּדּוּשִׁין עַד שֶׁיִּקְנוּ מִיָּדוֹ אוֹ עַד שֶׁיִּכְתֹּב בִּשְׁטָר וְכַיּוֹצֵא בּוֹ כְּמוֹ שֶׁיִּתְבָּאֵר בְּהִלְכוֹת מִקָּח וּמִמְכָּר. נִתְגָּרְשָׁה בְּתוֹךְ הַשָּׁנִים שֶׁקִּבֵּל עַל עַצְמוֹ לָזוּן אֶת בִּתָּהּ וְנִשֵּׂאת לְאַחֵר וּפָסְקָה גַּם עִמּוֹ שֶׁיִּהְיֶה זָן אוֹתָהּ הַבַּת כָּךְ וְכָךְ שָׁנִים לֹא יֹאמַר רִאשׁוֹן אִם תָּבוֹא לְבֵיתִי אֲזוּנָהּ אֶלָּא מוֹלִיךְ מְזוֹנוֹתֶיהָ לַמָּקוֹם שֶׁהִיא שָׁם אִמָּהּ. וְכֵן לֹא יֹאמְרוּ שְׁנֵיהֶם הֲרֵי אָנוּ זָנִין אוֹתָהּ כְּאַחַת אֶלָּא אֶחָד זָנָהּ וְאֶחָד נוֹתֵן לָהּ דְּמֵי מְזוֹנוֹת:
כסף משנה
17.
When a man marries a woman and makes a commitment to support her daughter for [an explicit number of] years, he is obligated to support her for [all] the years to which he committed himself, provided he made this commitment at the time of the woman's consecration.27Generally, such commitments are not binding, for the commitment does not have a specific scope. In most situations, only when a definite sum is mentioned is the commitment obligatory. (See Shulchan Aruch, Even HaEzer 114.)
If, however, he made the commitment [after] the kiddushin [were given], the commitment is not binding until he affirms it with an act of contract or composes a document to that effect, as will be explained in the laws of business transactions.28Hilchot Mechirah 11:15-17.
[The following rules apply when] a woman is divorced within the time that her husband committed himself to support her daughter, and she married another man who also committed himself to support her daughter for a particular number of years. The first husband does not have the prerogative to say: "If she comes to my house, I will support her."29Needless to say, he is obligated to support his divorcee's daughter if his divorcee does not remarry. There is a difference of opinion among the Rabbis if the husband is required to provide his divorcee's daughter with the full measure of support she requires, or he is merely obligated to give her the amount of money it would cost for him to support her in his own home. (See Shulchan Aruch and Ramah, Even HaEzer 114:6.) Instead, he must bring her support to the place where she is staying together with her mother. Similarly, both husbands do not have the prerogative of saying: "We will together provide for her support." Instead, one of the husbands must provide for her support, and the other must give her the financial value of her support.

הלכה יח
נִשֵּׂאת הַבַּת בְּתוֹךְ זְמַן זֶה הַבַּעַל חַיָּב בִּמְזוֹנוֹתֶיהָ. וּבַעֲלֵי אִמָּהּ שְׁנֵיהֶם כָּל אֶחָד וְאֶחָד נוֹתֵן לָהּ דְּמֵי מְזוֹנוֹת. מֵתוּ אֵלּוּ שֶׁפָּסְקוּ לָזוּן אוֹתָהּ אִם קָנוּ מִיָּדָן אוֹ שֶׁחִיֵּב עַצְמוֹ בִּשְׁטָר הֲרֵי זוֹ כְּבַעַל חוֹב בִּשְׁטָר וְטוֹרֶפֶת מְזוֹנוֹתֶיהָ מִנִּכְסֵיהֶן הַמְשֻׁעְבָּדִים עַד סוֹף הַזְּמַן שֶׁפָּסְקוּ. וְאִם פָּסְקוּ בִּשְׁעַת הַקִּדּוּשִׁין וְלֹא הָיָה שָׁם קִנְיָן הֲרֵי הֵם דְּבָרִים שֶׁלֹּא נִתְּנוּ לִכָּתֵב וְאֵינָהּ טוֹרֶפֶת בִּמְזוֹנוֹתֶיהָ:
כסף משנה
18.
[The following rules apply when the woman's] daughter marries during the time [in which her mother's husbands] obligated themselves to supply her with her sustenance. Her own husband is obligated to provide her with her sustenance, and both of her mother's husbands are obligated to give her the financial value of her support.
[Even when the men] who obligated themselves to support her die, if they affirmed their commitment to her mother with an act of contract or they composed a formal document recording their obligation, [the daughter] is considered to be a creditor whose claim is supported by a deed, and she has the prerogative of collecting her due from property that has been sold until the conclusion of the time period for which he committed himself.
If the commitment was made at the time of the kiddushin, and was not affirmed by an act of contract, it is a commitment that was not to be recorded in a contract,30As mentioned in the notes on Halachah 13, even if this commitment was recorded in a document, as long as a formal deed is not composed, the purchasers are not under any obligation. and [the daughter] does not have the prerogative of expropriating property [from purchasers] for her support.

נשים הלכות אישות פרק כג
Nashim Ishus Chapter 23