Reference for Bava Batra 318:9
וטעמא מאי אמר אביי נאמרה סיבה בבן ונאמרה סיבה בבעל מה סיבה האמורה בבעל אין הבעל יורש את אשתו בקבר אף סיבה האמורה בבן אין הבן יורש את אמו בקבר להנחיל לאחין מן האב
[Must it] not then [be concluded that it is] this that was meant: If a father was taken into captivity [where he died] and the son of his daughter died in the [home] country, or if the son of one's daughter was taken into captivity [where he died], and the father of his mother died in the [home] country; and it is not known which of them died first, [the estate] is to be divided between the heirs of the father and the heirs of the son. Now, if it were so,<span class="x" onmousemove="('comment',' That a son in the grave inherits the estate of his mother. ');"><sup>16</sup></span> granted even that the son died first, he should in his grave inherit [the estate] of the father of his mother and transmit it to his paternal brothers! [Must it] not consequently be inferred that a son in the grave does not inherit [the estate of] his mother to transmit [it] to his paternal brothers?