Sahih al-Bukhari 4605 - "They ask you for a legal verdict. Say: 'Allah directs (thus) about Al-Kalal,a (those who leave neither descendants nor ascendants as heirs). If it is a man that dies, leaving a sister, but no child, she shall have half the inheritance. If (such a deceased was) a woman who left no child, her brother takes her inheritance..." (V.4:176) | Criterion