1) THE "TAKANAH" OF "SHAKDU"
QUESTION: Rav Yosef quotes Rav Yehudah in the name of Shmuel who teaches that the reason one must get married on Wednesday and not on Sunday is the enactment of "Shakdu." The Rabanan were concerned for the honor of Jewish women and they enacted that a man must get married on Wednesday so that he spend three days (Sunday, Monday, and Tuesday) preparing a respectable Se'udah for the wedding. Since one is required to get married on Wednesday because of the enactment of "Shakdu," if an engaged couple's twelve-month period of Erusin ends on a Sunday, the man is not obligated to pay for his bride's support ("Mezonos"), since he can justifiably claim that he is not required to marry her until Wednesday due to the Takanah d'Rabanan.
The wording of Rav Yehudah in the name of Shmuel implies that the Mishnah (which states that the reason for delaying the wedding until Wednesday is to provide the opportunity for the man to go to Beis Din on Thursday if he has a Ta'anas Besulim) does not provide sufficient reason for why the husband is justified in not paying the wife when the twelve-month period of Erusin ends on a Sunday and he delays marrying until Wednesday. It is only the additional reason of "Shakdu" which the Beraisa introduces that justifies not paying the wife "Mezonos" in such a situation.
Why is the reason of "Shakdu" necessary in order to exempt him from Mezonos? The Mishnah teaches that one must get married on Wednesday because of the Takanah d'Rabanan; that Takanah should be sufficient reason to exempt him from paying Mezonos!
ANSWERS:
(a) TOSFOS (DH v'Tinasei), as explained by the SHITAH MEKUBETZES and the MAHARSHA, explains that there is another factor which requires that a person get married on Wednesday. The Gemara (5a) says that one should get married on Wednesday in order to perform the Be'ilas Mitzvah at the beginning of Thursday (Wednesday night), because it was on the original Thursday that Hash-m gave a Berachah to the fish to multiply. Therefore, it is a good omen if one performs the Be'ilas Mitzvah on Thursday (Wednesday night).
Had the Beraisa not taught the reason of "Shakdu" for marrying on Wednesday, one might have thought that the Mishnah instructs that one should get married on Wednesday (and not Sunday) simply because of the Berachah that Hash-m gave to the fish. If that would be the reason to get married on Wednesday (as opposed to Sunday), however, then it would not suffice to exempt the husband from paying Mezonos to his wife when the twelve-month period of Erusin ends on Sunday. The good omen of the Berachah of the fish does not obligate one to get married on Wednesday. It is merely a recommendation that he do so, as good advice. Since the Berachah of the fish does not obligate him to get married on Wednesday, he cannot claim that he is unable to get married on Sunday, and thus he would have to pay Mezonos to his wife. Furthermore, the reason of Berachah does not exempt him from paying Mezonos because it benefits him and not her, since he is the one who is obligated to fulfill the Mitzvah of "Piryah v'Rivyah." Therefore he cannot exempt himself from paying Mezonos until Wednesday arrives because his delay until Wednesday is for his benefit and not hers.
However, now that the reason for getting married on Wednesday is "Shakdu," it is an established enactment of the Rabanan that one is obligated to get married on Wednesday and is not permitted to get married on any other day. Furthermore, the enactment of "Shakdu" is for her benefit and not for his benefit, and therefore he may claim that he cannot marry her until Wednesday and exempt himself from paying Mezonos until then.
(b) The TOSFOS HA'ROSH (quoting his Rebbi, the MAHARAM) suggests a different explanation for the Gemara, according to which our question is also answered differently.
From the words of the Mishnah it is not clear that a person must get married on Wednesday. Perhaps the Mishnah means that one merely must perform the Be'ilas Mitzvah on Wednesday night; he may get married on any day of the week as long as he waits to do the Be'ilas Mitzvah until Wednesday night (either because of the Berachah to fish, or because of Ta'anas Besulim). Even though the Mishnah says that "a Besulah must get married on Wednesday," perhaps the Mishnah means that the Be'ilah must be done on Wednesday night and it merely uses a nicer way of expressing this. Alternatively, the Mishnah means that since the Be'ilas Mitzvah cannot be done until Wednesday night, it is advisable to get married then and not earlier.
Accordingly, if the twelve-month period ends on a Sunday, then she should be able to insist on getting married then (and just waiting until Wednesday night for the Be'ilah), and if he does not agree to get married he must pay her the Mezonos. However, now that the Beraisa teaches that the Rabanan instituted getting married on Wednesday because of "Shakdu," it is clear that the Mishnah is not discussing merely the Be'ilas Mitzvah, but it is discussing the date of the actual marriage. The Rabanan instituted that the marriage itself must be on Wednesday (so that he can begin to prepare the wedding banquet three days in advance). Since the enactment was that he get married on Wednesday (that is, the Rabanan do not permit him to get married until then), he may exempt himself from paying Mezonos if the twelve-month period ends on a Sunday.

2b----------------------------------------2b

2) "EIN GET L'ACHAR MISAH"
QUESTION: The Gemara quotes a Mishnah in Gitin and explains that the Reisha of the Mishnah teaches that a man may not divorce his wife after his death -- "Ein Get l'Achar Misah." RASHI (DH Mes Hu) explains that the reason is because "dead people cannot divorce" -- "Ein ha'Mesim Megarshim."
Why does the Mishnah need to teach that a man cannot divorce his wife after his death? After the man dies, he is not married anymore and there is no longer any Kidushin; of course the Get cannot take effect! Furthermore, why does Rashi say that the Mishnah teaches that "dead people cannot give divorces"? The reason the Get does not take effect is because the woman is no longer married when her husband dies!
In fact, in Gitin (9b) -- where the Gemara teaches that a Shtar Shichrur (a document of release for an Eved) and a Shtar Mecher (a document of sale) cannot take effect after the death of the owner, RASHI (DH Lo Yitnu and DH v'Ein Shtar) explains that the reason is because when the owner dies, the Eved or property no longer belongs to him, and thus he has no right to set the Eved free or to sell the property. Why does Rashi here not give the same explanation -- that after a man has died the woman is no longer his wife to divorce? (See KETZOS HA'CHOSHEN 188:2.)
ANSWER: The Gemara is discussing a case in which the husband dies with no children and his wife falls to Yibum. If the Get is valid, it exempts her from Yibum (as Rashi explains in DH Eino Get). The Zikah of Yibum is considered, in a sense, like a continuation of the bond of marriage, since the Zikah to the Yavam comes only as a result of the marriage of the woman to his brother who died. (See TOSFOS to Kidushin 4b, DH Mah l'Yevamah, in the name of Rebbi Elazar mi'Shazna.)
Therefore, one might have thought that since an element of the original Kidushin remains, the Get can be effective in divorcing one's wife even after he has died. This is why the Mishnah must teach that "Ein Get l'Achar Misah" -- even though a part of the Kidushin does remain after the husband's death in a situation of Yibum, nevertheless "Ein ha'Mesim Megarshim," as Rashi explains.
(This also explains why Rashi, in DH Eino Get, writes that the practical consequence of the Get not being valid is that the wife falls to Yibum. At the end of the Daf, Rashi mentions a different consequence -- that the woman does not become Pesulah l'Kehunah if the Get is not a valid Get. Why does Rashi not mention that consequence here? The answer is that Rashi wants to point out that the case of the Mishnah must be a case in which the woman falls to Yibum, because otherwise there is no Chidush in teaching that "Ein Get l'Achar Misah.")

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