Kiddushin 34a: Women are obligated in the mitzvah of mezuzah. But why not learn from the juxtaposition of mezuzah to learning Torah that just as women are exempt from learning Torah, they are exempt from mezuzah? Because the verse about mezuzah ends, “So that your lives may be long.” Do only men want to live long and not women?
ונקיש מזוזה לתלמוד תורהִ! לא סלקא דעתך, דכתיב: (דברים יא) למען ירבו ימיכם, גברי בעי חיי, נשי לא בעי חיי?
A woman was becoming religious and her husband was not. She wanted to buy mezuzos for the house, but her husband said, “The rabbis overcharge for them just to line their pockets. I won’t waste money on that.” So she asked her rav if she was allowed to steal her husband’s money to buy mezuzos. She would tell him that they were donated by a kiruv organization. The rav was uncertain what to answer: of course one may not steal to perform a mitzvah, but here one could argue that a husband is obligated to give his wife a house, and part of a house is the mezuzos. Thus, taking his money for something he is obligated to do is not stealing.
However, Rabbi Yitzchok Zilberstein ruled that she should not do it. First of all, it was not her house, but her husband’s, so she was not obligated in the mitzvah of mezuzah – only he was. Second of all, if he ever found out, it would be a tremendous chillul Hashem for him to think that we steal in order to do mitzvos.
[In Read and Remember p. 332, I bring a similar story in which Rav Elyashiv zt”l was the posek, and ruled that she should not buy the mezuzos because the Mordechai says that one who has no money to buy mezuzos may still live in the house. However, here we are considering a different angle: the husband should be obligated to buy her the mezuzos as part of his obligations toward her as a husband.
The answer that “it’s not her house” doesn’t seem to be sufficient, either, because מזוזה חובת הדר היא. On p. 111 I brought the story of Reb Zalman Volozhiner who did not want to enter a house because the mezuzah was in the wrong place. It did not make a difference to him that the house belonged to someone else. Only when the owner declared the house hefker did he enter.
Rather it would seem that forcing a husband to fulfill his obligations to his wife is something only beis din can do. Stealing and going about it secretly is not allowed. Perhaps she did not want to challenge him openly before a beis din; in that case she was mochel on her rights.]