Is the interpretation that the first Kalalah verse (Surat An-Nisa) refers to uterine brothers and sisters, and the second to full or consanguine brothers and sisters, an act of ijtihad? And can one make a will for a third in the first case, but be prevented from doing so in the second?

The first verse concerns maternal half-siblings, and this is a matter of consensus, while the second verse concerns full siblings or paternal half-siblings. Bequeathing one-third of the estate is prescribed for the deceased in both cases, due to its established legitimacy through the general verse of bequests. The obligation has been abrogated, but the recommendation remains for those who are not heirs.