Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said concerning the verse "Allah instructs you concerning your children: for the male, the like of the share of two females" [Surah al-Nisa: 11]: Inheritance used to be for the children, and bequest was for the parents. Allah Almighty abrogated of that what He willed: He assigned to the male child the like of the share of two females, assigned to the parents a sixth each, assigned to the husband a half or a quarter, and to the wife a quarter or an eighth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12292