Ketubot 71B

בבגדי צבעונין״! הכא במאי עסקינן ⁠— בדברים שבינו לבינה.

with colored garments, as not wearing colored garments can cause shame to her as well as to her husband. But vows that affect her alone are not considered vows of affliction. The Talmud answers: Here we are dealing with a case where she vowed not to adorn herself with regard to matters that are between him and her, meaning that she vowed not to use a substance that removes her pubic hair. This is considered a matter between him and her, since the hair could interfere with sex.

הניחא למאן דאמר דברים שבינו לבינה הבעל מיפר. אלא למאן דאמר אין הבעל מיפר, מאי איכא למימר? דאתמר: דברים שבינו לבינה, רב הונא אמר: הבעל מיפר, רב אדא בר אהבה אמר: אין הבעל מיפר, שלא מצינו שועל שמת בעפר פיר.

The Talmud asks: This works out well according to the one who said the husband can nullify his wife’s vow if it relates to matters that are between him and her, i.e., that disrupt normal, intimate sex between them. But according to the one who said the husband cannot nullify such vows, what can be said? The amora’im had a dispute concerning this question, as it is stated: With regard to vows related to matters that are between him and her, such as the example above, Rav Huna said that the husband can nullify his wife’s vow, while Rav Adda bar Ahava said the husband cannot nullify his wife’s vow, since it does not interfere with sex between them. Rav Adda bar Ahava explains his opinion with an analogy: Since we have not found a fox that died in the dirt of a hole where it lives, so too here, although she grows her pubic hair, he will not be harmed by it, since he is familiar with her body.