Gemara

(Beraisa): "She'ero (his close relative)" refers to the father. It teaches that if Reuven dies, his father inherits him before Reuven's brothers;

Suggestion: Perhaps Reuven's father inherits before Reuven's son!

Rejection: "Ha'Karov" teaches that the closest relative comes first.

113b (Rav Shmuel bar Rav Yitzchak): "V'Yorash" equates the second inheritance to the first inheritance. Just like sons inherit before daughters, also in the second inheritance (Tosfos - sons of a child inherit before the child's daughters; Rashbam - brothers inherit before sisters).

115a (Beraisa) Question: Perhaps "u'Ven" teaches only a son (that he inherits before a daughter)! What is the source for a child or grandson of a son? (E.g. if Dosan died before his father Eli'av, and Dosan left a child or grandson, Dosan's descendant inherits Eli'av, and Eli'av's daughters do not.)

Answer: "Ein Lo" - we read this 'Ayen' (investigate).

Just like we look for descendants, we also look for ancestors. (If Dosan left no descendants, and also his father left none, we look for his father's father (or his descendants)... even if we must go until Reuven (ben Yakov Avinu).

130a (Mishnah): If Reuven said 'Ploni (a stranger) will inherit me', and Reuven has a daughter, or he said 'my daughter will inherit me', and he has a son, this does not take effect;

R. Yochanan ben Brokah says, it takes effect if he gives to someone fitting to inherit him.

(Beraisa - R. Yishmael, son of R. Yochanan ben Brokah): My father and Chachamim agree that if one stipulated that a relative should inherit in place of a daughter, or a daughter in place of sons, the stipulation does not take effect. They argue when he stipulates that one daughter will inherit in place of all the daughters, or one son in place of all the sons. My father says that it takes effect, and Chachamim say that it does not.

159a: If Reuven sold his father's property in Yakov's lifetime, and Reuven died, and Yakov died, Reuven's son (Chanoch) takes from the buyers. He can say 'I inherit Yakov - "Tachas Avosecha Yihyu Vanecha."'

159b (Rav Acha bar Minyomi): A Mishnah teaches that if a woman died after her son, he does not 'inherit' her in the grave, i.e. to pass her property to his paternal brothers.

Rishonim

Rif (59b): The Halachah follows R. Yochanan ben Berokah. If a Shechiv Mera wrote all his property to a son, he only made him an overseer. This is a Halachah without a reason; we do not apply it to any other case.

Rambam (Hilchos Nachalos 6:1): One cannot bequeath to one who is not able to inherit him, nor to uproot inheritance, even though it is money.

Rambam (2): If he had many heirs, e.g. sons, brothers or daughters, and said when he was Shechiv Mera 'Ploni my brother should inherit me out of my brothers, or 'Plonis my daughter should inherit me out of my daughters', his words are fulfilled.

Rambam (Hilchos Zechiyah 9:5): If a Shechiv Mera wrote all his property to one who could inherit him, he receives it like an inheritance, e.g. the heir was one of his daughters, grandsons, brothers, or other heirs.

Ohr Some'ach (Nachalos 2:14): Rishonim argue about whether brothers inherit due to their own power, or due to Mishmush. From this Rambam, we see that he holds that it is due to Mishmush.

Tosfos (Bava Basra 108b DH Yachol): Why did the Torah need to write that uncles inherit? We could learn from Mishmush (when there are no descendants, ancestors inherit)! The Ri says that had the Torah not written uncles, we would not know that Mishmush goes back to ancestors. Why did the Torah need to write that brothers inherit? We could learn from Mishmush! It taught about brothers to teach that a father inherits before brothers, but not before a daughter.

Poskim

Shulchan Aruch (CM 281:1): One cannot bequeath to one who is not able to inherit him, nor to uproot inheritance. However, if he had many heirs, e.g. sons, brothers or daughters, and said when he was Shechiv Mera '(only) Ploni my brother should inherit me among my brothers, or '(only) Plonis my daughter should inherit me among my daughters' (Rema - or he gave more to one than to another), his words are fulfilled.

Beis Yosef (DH u'Mah she'Chosav Aval): The Halachah follows R. Yochanan ben Berokah, according to his son R. Yishmael, that one may transfer inheritance only to inherit part.

Question (Ketzos ha'Choshen 2): How can he stipulate to bequeath to a particular brother? A father (who already died) inherits before his descendants, and his descendants receive equally from him! Perhaps the Rambam (from whom this Halachah is taken) learned from the Tosefta (7:5), which says that giving to a daughter among sons or to a brother among daughters does not work. This implies that giving to a brother among brothers works! Also the Rif says so. Even though brothers inherit due to the father, since the father inherits due to his (the Shechiv Mera's) power, he (the Shechiv Mera) can bequeath to whom he wants. Similarly, if Eli'av's son Dosan died, Eli'av can stipulate that one of Dosan's sons will inherit everything. Even though Dosan's sons inherit due to Dosan's rights, Dosan inherits due to Eli'av, therefore, Eli'av can decide that one of them receive everything.

R. Akiva Eiger (1:132): Sefer ha'Terumos says that if a Shechiv Mera (Shimon) gave his property to one of his nephews, we do not say that the nephew comes from his grandfather's rights. The Poskim connote that R. Yochanan ben Berokah's law applies in every case. We can learn from Tosfos, who asked why the Torah needed to write that brothers inherit; we could learn from Mishmush. It makes a difference when one said that one of his brothers will inherit! Rather, we must say that Tosfos holds that even if one inherits through MIshmush, the Shechiv Mera can designate any partial heir to inherit everything.

Chazon Ish (ibid. DH ha'Gaon): Also the Rambam (Hilchos Zechiyah 9:5) says so, but one could say that the Rambam holds that a creditor would not inherit, for the nephew can say I inherit my uncle.' Sefer ha'Terumos says that only a grandchild can say that he inherits directly. R. Akiva Eiger proved that an heir who has rights to inherit directly, also has rights to inherit his dead relative in the grave.

Kovetz Shi'urim (Bava Basra 333): Regarding Mishmush, does the second (dead) heir inherit the first, and the third heir inherits from the second? Or, a Mes cannot acquire, so the third inherits the first, for he is in place of the second. The latter is correct. A relative who inherits is Pasul for testimony. Rashi (Sanhedrin 27b) says that a nephew (Elazar) cannot testify for his mother's brother (Nachshon), for Elazar inherits Nachshon. If a Mes inherits in the grave, Elazar inherits his mother, and not Nachshon! Also, we equate the second inheritance to the first. I.e. a man died, and his sons and daughters inherit their grandfather (Tosfos 113b DH Makish). If a Mes inherits in the grave, this is first inheritance, and no Hekesh is needed (to teach that the sons alone inherit)! Tosfos says that we learn that a grandchild exempts from Yibum from inheritance, i.e. one inherits his grandfather. If he inherits his father in the grave, there is no proof to Yibum. The Ramah says that a son who died does not inherit his mother in the grave to bequeath to his paternal brothers because the live brother is not a relative of the mother. If he inherits his dead brother, he need not be a relative of the mother! All this shows that the third inherits the first. This resolves the questions of the Ketzos ha'Choshen and R. Akiva Eiger. Maharam bar Baruch (928) says that R. Simchah said that according to the Ge'onim who say that a Mumar (apostate) does not inherit his father, the Mumar's son inherits his grandfather mid'Oraisa.- "Tachas Avosecha Yihyu Vanecha." The Yerushalmi asks why a grandson cannot do Yi'ud (marry his grandfather's Amah Ivriyah), but a grandson is like a son for inheritance. If a grandson inherits through his dead father, we do not consider him a son of his grandfather!