17b----------------------------------------17b

1) "MEYUCHADIN B'NACHALAH" -- BROTHERS WHO SHARE AN INHERITANCE
QUESTION: The Gemara discusses the source for the Halachah that Yibum is practiced only by a brother who shares the same father as the deceased. The Gemara cites two sources. The first is the verse of Yibum which says, "When brothers dwell together (Yachdav)" (Devarim 25:5), which teaches that they must be "Meyuchadin b'Nachalah" -- "together in the inheritance." The second source is the the verse of Yibum which says, "When brothers (Achim) dwell together" (ibid.), from which a Gezeirah Shavah to the word "Achim" mentioned with regard to the sons of Yakov (Bereishis 42:13) is derived: just as the sons of Yakov had the same father but different mothers, so, too, the obligation of Yibum applies only to brothers who have the same father.
RASHI explains that "Meyuchadin b'Nachalah" means that the brothers must be able to inherit each other if the other dies.
However, at the end of the Sugya the Gemara says that had the Torah taught only the word "Achim," one would have thought that the obligation of Yibum applies even to an uncle and a nephew (for example, when the uncle dies childless, the nephew is obligated to do Yibum with his uncle's wife), because they, too, are referred to as "Achim," as Avraham told Lot, "... for we are brothers (Achim)" (Bereishis 13:8). Hence, the verse adds the word "Yachdav" to teach that only actual brothers are obligated in Yibum. Only brothers are "Meyuchadin b'Nachalah," and not an uncle and a nephew.
Rashi there explains that "Meyuchadin b'Nachalah" means that they share the inheritance when their father dies. This definition of "Meyuchadin b'Nachalah" clearly differs from the definition which Rashi gives earlier. Why does Rashi change his explanation? (RASHBA)
ANSWER: The RITVA answers that "Meyuchadin b'Nachalah" means that they share an inheritance in all ways; they divide an inheritance that they receive from someone else, and they are able to inherit each other.
The Riva explains that both meanings of the verse are implicit in the Sugya; Rashi gives the two different explanations because he follows the train of thought of the Gemara. When the Gemara first mentions that the brothers must be "Meyuchadin b'Nachalah" in order to do Yibum, its intention is to exclude brothers from the same mother (and from different fathers). Such brothers do share an inheritance if their mother leaves behind possessions when she dies. However, they do not inherit each other's property, because when one brother dies (with no children) his property goes to his father and then to his father's heirs. Thus, "Meyuchadin b'Nachalah" means that they must be able to inherit each other, and it excludes brothers who share the same mother and not the same father.
In contrast, in the case of an uncle and a nephew (such as Avraham and Lot), they could inherit each other if they have no other close relatives, and thus they qualify for the first definition of "Meyuchadin b'Nachalah." The inheritance could go from the uncle to the nephew (via the nephew's father, the uncle's brother), as well as from the nephew to the uncle.
However, an uncle and a nephew share no inheritance from any single person. (If the uncle's father dies, the uncle splits the inheritance with his brother. Even if that brother is dead and the inheritance goes to the nephew, he is not actually splitting it with his uncle, but rather his father splits it with his uncle and then he inherits it from his father.)
2) AVRAHAM AND LOT WERE "ACHIM"
QUESTION: The Gemara discusses the sources for the law that Yibum is practiced only between brothers who share the same father. One of the sources is the verse, "When brothers (Achim) dwell together" (Devarim 25:5), from which a Gezeirah Shavah to the word "Achim" mentioned with regard to the sons of Yakov (Bereishis 42:13) is derived: just as the sons of Yakov had the same father but different mothers, so, too, the obligation of Yibum applies only to brothers who have the same father.
The Gemara asks that the verse also says "Achim" with regard to Avraham and Lot: "... for we are brothers (Achim)" (Bereishis 13:8). Perhaps the obligation of Yibum applies even to an uncle and a nephew (for example, when the uncle dies childless, the nephew is obligated to do Yibum with his uncle's wife), because they, too, are referred to as "Achim." The Gemara answers that the Gezeirah Shavah refers only to the sons of Yakov; the word "Achim" there is Mufneh ("open" and available to be used for a Derashah, and it is not used for any other teaching), while the word "Achim" in the verse of Avraham and Lot is not Mufneh.
The Gemara at the end of the Sugya concludes that both the word "Achim" and the word "Yachdav" (see previous Insight) in the verse of Yibum are necessary to teach that Yibum applies only to brothers from the same father; the word "Achim" alone does not suffice. The Gemara says that had the Torah not taught "Yachdav," one would have applied the Gezeirah Shavah of "Achim" from Avraham and Lot, because the word "Achim" there is Mufneh since it should have said "Re'im" instead of "Achim."
What does the Gemara mean? The Gemara just said that the word "Achim" in the verse of Lot is not Mufneh. Why does the Gemara now say that it is Mufneh?
Moreover, if "Achim" in the verse of Lot indeed is Mufneh as the Gemara now says, the Gemara should explain what is derived from that word, since "Yachdav" and "Achim" in the verse of the sons of Yakov together teach that the obligation of Yibum applies only to brothers and not to an uncle and a nephew. The word "Achim" in the verse of Lot remains Mufneh; what law does it teach? (MAHARSHA)
ANSWERS:
(a) The RITVA answers that, in truth, the word "Achim" in the verse of Lot is not Mufneh, as the Gemara originally asserts. The verse could not have used the word "Re'im" because Avraham's intention was to express that he and Lot were more than just friends to each other; they were as close as brothers. (The Maharsha explains that the verse uses the word "Achim" instead of "Re'im" to teach that one's grandchildren are considered like his children.) When the Gemara says that without the word "Yachdav" one would have thought that "Achim" of Lot is Mufneh, it means that one would have mistakenly thought that it is Mufneh and that its purpose is to teach a Halachah in the laws of Yibum. "Yachdav" teaches that "Achim" of Lot is not Mufneh and teaches nothing about Yibum.
(b) The RAMBAN and RASHBA answer that even when the Gemara says that "Achim" in the verse of Lot is Mufneh, it does not mean that it is actually Mufneh. The Gemara knows that the word "Achim" is needed to teach that Avraham felt as close as a brother to Lot. Rather, when the Gemara says that the word is Mufneh it means that when the Torah says "Achim" in the verse of Yibum, its intention is to teach that these brothers should not be compared to any specific "Achim" mentioned elsewhere in the verses, but rather that Yibum applies to any relatives to whom the verse refers with the word "Achim." If the word "Achim" appears in reference to an uncle and nephew, then it teaches that the word "Achim" in the verse of Yibum also includes that relationship (of uncle and nephew) for Yibum (it is a "Giluy Milsa").
This is what the Gemara means when it says that the verse of Lot should have said "Re'im," which is the intention of the verse. The fact that it instead says "Achim" teaches that the word "Achim" in the verse of Yibum describes a relationship of uncle and nephew as well. "Yachdav" therefore teaches that the word "Achim" in the verse of Yibum refers only to a specific type of Achim -- actual brothers who share the same father.