Commentary for Numbers 27:9

AND IF HE HAVE NO DAUGHTER, THEN YE SHALL GIVE HIS INHERITANCE UNTO HIS BRETHREN. Our Rabbis have received a tradition¹⁶⁴Baba Bathra 115a. that a father inherits his son if he [the son] dies without any children, but Scripture, however, did not mention this. The reason [for this omission] is that in the laws of inheritance [the rule is]: “Whoever can bequeath an inheritance to his relations can inherit [from them],” since their relationship is mutual. Now since Scripture stated that a son inherits his father, [it is self-understood that] the father also inherits his son [if the son died without direct descendants, but left, for example, brothers]. And furthermore, the [primary law of] inheritance is [that it follows the direct] line of [descent of] successors [of the progenitor] according to his [direct] descendants, and does not go by means of a side-succession [such as to a brother; hence the father gets it back from his son].¹⁶⁴Baba Bathra 115a. If so [the meaning of the verse] then ye shall give his inheritance unto his brethren is the inheritance which the father inherits in the grave [in a direct line back from his son]; and from him [the father, who is already dead], it comes [again in a direct line] to the brothers [who survive the deceased son]. But [although according to the tradition of our Rabbis, a father inherits his son who dies without any children, even if the son has surviving brothers], Scripture yet did not want to say: “And if he have no daughter, then ye shall give his inheritance unto ‘his [surviving] father,’” [but instead states that you shall give his inheritance ‘to his brothers’] since the Torah speaks “in a way of blessing” [and therefore mentions only the children or brothers who inherit], for it does not [want to speak about] those who are “cut off” [i.e., a case where the dead man is “cut off” in his youth, during the lifetime of his father]. And perhaps [the reason why Scripture does not mention it explicitly is] because it did not happen to any of those who entered the Land, that a father [outlived and] inherited his son, but the sons always had direct descendants to inherit them; for it is about them [those who entered the Land] that Scripture speaks.

ואם אין לו בת ונתתם את נחלתו לאחיו, “and if he had no daughter either, you will give his inheritance to his surviving brother.” Rabbi Avraham Ibn Ezra understands the word “his brother” to include either a brother by his father or a brother by his mother, all of whom take precedence in their claim over brothers of the deceased father, and, of course, over the brothers of the deceased’s mother. However, our sages in Baba Batra 110 state that the mother is not included in the term משפחה mentioned in verse 11 so that there cannot be a question of brothers of the mother being in line for this inheritance at all. Whereas a son inherits his mother, his mother does not inherit him (if he predeceases her) under any circumstances (Baba Batra 108).
A sister inherits her brother if he has neither a surviving father nor brother, just as the daughter inherits when there is no surviving male heir. (Compare Maimonides Hilchot Nachalot 1,3). Accordingly, the word לאחיו in our verse includes both brother or sister as the case may be. After the paragraph has informed us that the son inherits the father, it follows that if the sequence of death of father and son is reversed, the father inherits his son. The Torah did not want to spell this out directly as the fact that a father has to mourn the death of his son is a tragic occurrence. Whereas the Torah delights in mentioning instances of blissful occurrences it shrinks from outright references to tragic occurrences when avoidable. The principle we derive from all this is that anyone who is entitled to inherit from a certain person can also bequeath to such a person as the family relationship is identical in either direction. Seeing this matter is simple logic, the Torah did not have to spell it out as it wanted to avoid the painful emotional associations involved in contemplating fathers inheriting their children. Alternatively, the fact that the Torah did not bother to spell out this aspect of the legislation is a concealed blessing, i.e. in an Eretz Yisrael in which society follows the Torah-oriented way of life fathers will never have occasion to inherit their sons, i.e. make use in practice of this legislation. (Compare Nachmanides).

VV. 9-11. ואם אין לו בת וגו׳ ואם אין לו אחים וגו׳ ואם אין אחים לאביו וגו׳: ונתתם נחלתו לשארו הקרב אליו ממשפחתו. Die Verse 9-11 besprochenen Fälle sind nur Beispiele, für welche hier zuletzt das Grundprinzip gegeben wird, nach welchem diese und alle ferneren hier nicht weiter ausgeführten Fälle zu beurteilen sind. Dies Grundprinzip konstruiert sich aus drei Begriffen: שארו, die Blutsverwandtschaft, — הקרב, die Nähe dieser Verwandtschaft, so dass הקרוב קרוב קודם: der nächste Verwandte dem entfernteren vorangeht, und endlich: ממשפחתו, die Verwandtschaft muss innerhalb des Begriffs משפחה liegen, die Verwandten müssen zur משפחה der Verstorbenen gehören. Der Begriff משפחה konstruiert sich aber nur durch die Abstammung von einem Vater, nicht aber durch die Mutter. אחים, Brüder im Erbrecht sind z. B. nur die von einem Vater Erzeugten, nicht die von einer Mutter Geborenen. Söhne einer Mutter von verschiedenen Vätern gehören zu verschiedenen משפחות. Söhne eines Vaters von verschiedenen Müttern zu derselben:משפחה משפחת אב קרויה משפחה משפחת אם אינה קרויה משפחה דכתיב למשפחותם לבית אבותם (Baba Batra 109b). Die nächsten Verwandten eines Verstorbenen sind fürs Erbrecht seine Kinder und zwar in erster Linie seine Söhne. Vertritt doch der Sohn auch den Vater in יעוד (Schmot 21, 9) und שדה אהוזה (Wajikra 25, 25 und Baba Batra 108b). Ist kein Sohn und keines Sohnes Nachkomme da, so ist nach Vers 8 die Tochter oder ihre Nachkommenschaft die Erbin.