Reference for Nedarim 30:12

דאמר רב כהנא תשמישי עליך כופין אותה ומשמשתו דשעבודי משעבדת ליה הנאת תשמישך עלי אסור שאין מאכילין לו לאדם דבר האסור לו:

For R. Kahana said: [If a woman says to her husband,] 'Cohabitation with me be forbidden to you,' she is compelled to grant it, since she is under an obligation to him. [But if she says,] 'The pleasure of cohabitation with you be forbidden me,' he is forbidden [to cohabit]. Since one may not be fed with what is prohibited to him.<span class="x" onmousemove="('comment',' So here too. Where the husband or wife make a vow, depriving the other if his or her rights, it is invalid. But if the vow deprives its maker from the enjoyment of his or her privileges, it is valid, though the other is affected thereby too. ');">⁹</span>

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