Chasidut for Bava Batra 233:5
רבי שמעון בן אלעזר אומר
To what, however, may, according to the tales of the tribes of their fathers<span class="x" onmousemove="('comment',' Those who came out of Egypt. ');"><sup>3</sup></span> they shall inherit, he applied? — [To the following:] This [manner of] inheritance is different from all [other modes of] inheritance<span class="x" onmousemove="('comment',' Lit., 'inheritances'. ');"><sup>10</sup></span> in the world; for, in [the case of] all [other] successions in the world, the living are heirs to the dead but, in this case, the dead were heirs to the living.<span class="x" onmousemove="('comment',' Those who entered Canaan received shares according to their number, but the total of the shares was again divided in accordance with the number of their fathers who came out of Egypt. If two brothers, for example. came out of Egypt and died, and five sons of the one, and one son of the other entered Canaan, every son received a share, Six shares being allotted to the six sons. All these shares were then transferred to their fathers whose number was two (the dead being heirs to the living), and divided into two shares, each, of course, representing three of the original shares. The five sons thus received between them three of the original shares only, while the one son received for himself alone also three such shares. ');"><sup>11</sup></span> Rabbi said: I will give you an example to which this thing may be compared. To two brothers, priests, who were in one town. One had one son and the other had two sons, and these went to the threshing-floor.<span class="x" onmousemove="('comment',' To collect their priestly dues. ');"><sup>12</sup></span> He who has one son receives one portion, and the one who has two sons receives two portions. They<span class="x" onmousemove="('comment',' The two brothers. ');"><sup>13</sup></span> [then] return [with the three portions] to their father,<span class="x" onmousemove="('comment',' Whose estate has not yet been divided between them, in which case all acquisitions are pooled in the estate (cf. infra 137b). And since the three shares thus revert to their father, they inherit from him in equal shares. ');"><sup>14</sup></span> and re-divide [the total] in equal shares. R. Simeon b. Eleazar said:
Kedushat Levi
Since the generation who left Egypt as adults did not get to the land of Israel, only their sons, it follows that the parents did not achieve their שלימות, “maturity” until their sons had made the Land of Israel their ancestral heritage. This is the meaning of “the dead inherited the living.”
This statement in the Talmud about the dead inheriting the living, also explains another statement in the Talmud Sanhedrin 104, according to which a son [while alive Ed.] can confer spiritual merits on his [deceased] father, whereas his deceased father cannot confer merits on his surviving son. The Talmud bases this on the example of the second generation of the Israelites bestowing merits on their fathers after they carried out the task set by G’d for this people of settling in the Holy land and observing the Torah there. Avraham after his death, or Yitzchok, after his death, could not confer merits on their respective sons that these had not acquired during their respective lifetimes.