Responsa for Bava Batra 250:3
שלחו מתם הלכתא כוותיה דרב ענן ולאו מטעמיה הלכת' כוותיה דרב ענן דבעל לא ירית ולאו מטעמיה דאילו רב ענן סבר אע"ג דהוה לי' ברא לברתיה לא ירית ולא היא דאילו הוה ליה ברא לברתיה ודאי ירית ובעל היינו טעמא דלא ירית משום דהוה ליה ראוי ואין הבעל נוטל בראוי כבמוחזק
The law is in accordance with [the statement] of R. Anan; but not because of his reason. 'The law is in accordance with [the statement] of R. Anan' [in] that the husband is not to be the heir. 'But not because of his reason', for, whereas R. Anan holds the opinion [that] even though his daughter had a son he would not be heir,<span class="x" onmousemove="('comment',' Since he excludes the heirs of the heirs. ');"><sup>6</sup></span> [the law] is not [so]; for had his daughter had a son he would certainly have been heir.<span class="x" onmousemove="('comment',' The son of a daughter (in the absence of sons and their lineal descendants), is entitled to be heir to his grandfather and is, therefore, included in the expression 'my heirs'. ');"><sup>7</sup></span> The reason why the husband is not heir is this: Because [the estate] was<span class="x" onmousemove="('comment',' When his wife died. ');"><sup>8</sup></span>
Teshuvot Maharam
A. As long as A's widow did not take an oath regarding her ketubah, A's entire estate belonged to his two daughters. A's son-in-law, being his wife's rightful heir, is, therefore, entitled to half of A's estate.
This Responsum was addressed to Rabbi Menahem.
SOURCES: L. 226; Mord. Sheb. 780. Cf. Israel Bruno, Responsa 21.