1) THE "MITZVAH" TO PLACE A MEZUZAH ON CITY GATES
QUESTION: The Gemara says that the word "bi'She'arecha" (Devarim 6:9) teaches that a Mezuzah must be placed even on the gates of provinces (Medinos) and cities (Ayaros). The Beraisa, when it mentions that such gates require a Mezuzah, says, "Yesh ba'Hem Chovas Mitzvah la'Makom" -- "they have the obligation of the Mitzvah for the Omnipresent."
The Beraisa's expression is unusually elaborate. Why does the Beraisa not say simply that these gates are "obligated to have a Mezuzah" ("Chayavin b'Mezuzah")?
ANSWER: The SI'ACH YITZCHAK answers that the Gemara teaches that the Mezuzah arouses Divine protection for Jewish homes and their inhabitants (Avodah Zarah 11a). Similarly, the Gemara later (11b) says that fulfillment of the Mitzvah of Mezuzah brings long life. (Tosfos in Menachos (44a) writes that for this reason even a rented home requires a Mezuzah; see Insights to Yoma 11:4.)
Since the Mezuzah affords Divine protection, one might have thought that a Mezuzah is necessary on the door of one's residence but not on the gates of the city. Since one's home is already protected because of the Mezuzah affixed to its door, there is no need to affix a Mezuzah to the gates of the city. The Beraisa therefore teaches that while it is true that the city gates do not need a Mezuzah for the sake of protection, they still need a Mezuzah because of Hash-m's Mitzvah -- "Chovas Mitzvah la'Makom."
2) A MEZUZAH MUST BE EXAMINED "TWICE EVERY SEVEN YEARS"
QUESTION: The Gemara quotes a Beraisa that says that the Mezuzah of a private home must be examined twice every seven years ("Shavu'a"), while the Mezuzah of a public building must be examined twice every fifty years ("Yovel").
What is the significance of these numbers, and why are they expressed in such an unusual manner? Does the Beraisa mean that a Mezuzah of a private home must be examined once every three and a half years, or does it mean that a Mezuzah may be examined literally twice in seven years, such as once after the first two years, and again after five years?
ANSWER: These requirements were enacted by the Rabanan. RAV CHAIM KANIEVSKY shlit'a (in his commentary to Maseches Mezuzah) records a dispute with regard to the reason for the different requirements.
(a) According to RASHI, a Mezuzah must be examined intermittently due to concern that it may have rotted or was stolen. The Rabanan did not require that a public Mezuzah be checked as frequently as a private one in order not to inconvenience the public. Had the public been obligated to examine their Mezuzos frequently, each person would pass the responsibility on to another person and the Mezuzos would not be examined at all.
(b) The TOSFOS YESHANIM explains that the reason why the Rabanan enacted such infrequent inspections for public Mezuzos is because of the danger that the inspectors faced due to the decrees issued by the foreign regime against the fulfillment of Mitzvos.
(c) The SEFER HA'ESHKOL says that private Mezuzos are more likely to become damaged by exposure to the elements than public Mezuzos. The large number of people who pass by the public Mezuzos ensures that public Mezuzos are watched carefully.
Rav Chaim Kanievsky adds that although the Beraisa's terminology ("twice in seven years" and "twice in fifty years") implies that one fulfills his obligation to examine his Mezuzah even if he examines it in two consecutive years out of seven, this is not the Halachah. It is clear from the Beraisa in Maseches Mezuzah that the obligation applies every three and a half years for a private Mezuzah, and every twenty-five years for a public one. The Beraisa here merely uses an abbreviated manner of speech (perhaps to avoid discussing half-years) when it discusses the obligation to examine Mezuzos. (D. Schloss)
3) A MEZUZAH ON A HOLY PLACE
QUESTION: The Gemara cites a verse that teaches that only the entranceway of a "Bayis she'Hu Chol," a non-sanctified house, requires a Mezuzah, but not the entranceway of a holy place, such as Har ha'Bayis, the Lishkos, or the Azaros. Similarly, the Gemara later (12a) cites a Beraisa in which Rebbi Yehudah implies that a holy place does not require a Mezuzah.
Earlier in the Gemara (10a), the Chachamim and Rebbi Yehudah argue whether the Lishkas Parhedrin needs a Mezuzah. The Gemara there says that the question in that case depends on other factors, such as whether an involuntary dwelling place ("Dirah Ba'al Korcho") requires a Mezuzah, and whether a temporary dwelling place ("Diras Arai") requires a Mezuzah. However, the Gemara there does not suggest (according to either opinion there) that the Lishkas Parhedrin should be exempt from a Mezuzah because it is a holy place. Why does the Gemara there not give this reason for why the Lishkas Parhedrin is exempt from a Mezuzah?
(a) The TOSFOS HA'ROSH explains that both the Chachamim and Rebbi Yehudah (on 10a) exempt the Lishkas Parhedrin from a Mezuzah because it is a holy place, as the Beraisa here says. This exemption, though, applies only mid'Oraisa. The dispute between the Chachamim and Rebbi Yehudah is whether the Lishkas Parhedrin requires a Mezuzah mid'Rabanan. Rebbi Yehudah says that it is an involuntary dwelling place, and thus it is exempt from a Mezuzah even mid'Rabanan.
(b) The RITVA suggests that both the Chachamim and Rebbi Yehudah argue with the Beraisa here and assert that a holy place requires a Mezuzah mid'Oraisa. The Beraisa (12a) in which Rebbi Yehudah himself implies that a holy place is exempt does not refer to the Mitzvah of Mezuzah at all, but rather it refers to the laws of Nega'im.
(c) The ME'IRI explains that when the Beraisa exempts a holy place from a Mezuzah, it exempts a place that is used for purposes of holiness, and not necessarily all places that are sanctified. The Lishkas Parhedrin is not used for a holy purpose when the Kohen Gadol resides there, and thus it requires a Mezuzah even though it is a sanctified place.
(d) The Me'iri suggests further that even if an area that is inherently sanctified does not require a Mezuzah regardless of how it is used, perhaps the Lishkas Parhedrin is not considered a holy place at all. RASHI (6a, DH mi'Beiso) writes that the Lishkas Parhedrin was not sanctified, and thus the Kohen Gadol was permitted to sit in the Lishkah (and, similarly, the Gemara's question that the Kohen Gadol's wife should be able to stay with him there is justified; see Insights there). The Lishkas Parhedrin did not have any sanctity, even that of Har ha'Bayis.
4) A MEZUZAH ON A RENTED HOUSE
QUESTION: The Gemara asks why the verse says "Beisecha" ("your houses") with regard to the Mitzvah of Mezuzah. The word "Beisecha" implies that only a man's house requires a Mezuzah, but not a woman's house. There is no difference, however, between a house owned by a man and a house owned by a woman; both are obligated to have a Mezuzah. The Gemara answers that the word "Beisecha" does not imply that the house of a man needs a Mezuzah but not that of a woman, but rather it teaches that the Mezuzah must be placed on the doorpost to the right of a person who enters the house ("Bi'ascha").
The Gemara in Menachos (44a), however, derives a different law from the word "Beisecha": a rented house does not require a Mezuzah during the first thirty days of the rental period, because it is not "your house." (When one rents a house for more than thirty days, he must affix a Mezuzah only because of Mar'is ha'Ayin.)
Why does the Gemara here not answer that "Beisecha" teaches the law that the Gemara in Menachos derives from this verse?
(a) TOSFOS in Menachos (44a) explains that the Gemara here maintains that even a rented house requires a Mezuzah mid'Oraisa, because it, too, needs protection. (This is in contrast to the assertion of the GILYON HA'SHAS here.) The only reason why such a house is exempt from a Mezuzah for the first thirty days is because it is not considered a dwelling place until one has dwelled there for thirty days.
RASHI also explains that a rented house requires a Mezuzah mid'Oraisa (Bava Metzia 101b and Avodah Zarah 21a, DH Chovas ha'Dar). In fact, Rashi derives the obligation (as opposed to the exemption) to affix a Mezuzah to a rented house from the word "Beisecha," which implies "Derech Bi'ascha" -- anyone who uses an apartment, whether he owns it or rents it, is obligated to affix a Mezuzah. Before thirty days have passed, one is exempt only because he has not yet made it clear that he intends to live there in a permanent manner (Rashi to Menachos 44a, DH veha'Socher).
(b) The RASHBA in Shabbos (131b, DH Ho'il) writes that a rented or borrowed house obviously does not require a Mezuzah mid'Oraisa. The Gemara could have given that answer here, but it chose to teach another law which is learned from the word "Beisecha."
TOSFOS in Menachos (ibid.) also concludes that a rented house is not obligated to have a Mezuzah mid'Oraisa. He explains that the verse says "Beisecha" twice, and the Gemara here is explaining the second "Beisecha." The first "Beisecha" indeed teaches that a rented house does not need a Mezuzah.