It should be clear that just as sons have a rightful share in their parents' inheritance, daughters also have a legitimate inheritance share according to Shariah. After the parents' death, if the sons take exclusive possession of the inheritance and deprive their sisters of their rightful share, it is not only impermissible, but also a grievous sin.
Brothers are obliged to give their sisters their due share in this world; otherwise, they will have to give it in the Hereafter, which will not be easy. There are severe warnings in the Hadith regarding this: Hazrat Saeed bin Zaid (may Allah be pleased with him) reports that the Messenger of Allah (peace be upon him) said, "Whoever usurps even a span (balisht) of land unjustly, on the Day of Resurrection, Allah will place around his neck, in the form of a shackle, pieces of land from all Seven Earths equivalent to the piece of land he usurped unjustly."
In another Hadith, Hazrat Anas (may Allah be pleased with him) narrates that the Messenger of Allah (peace be upon him) said, "Whoever cuts off the inheritance of his heir (i.e., does not give him his due share), Allah will cut off his inheritance in Paradise on the Day of Resurrection."
Allah the Almighty has clearly and explicitly mentioned the laws of inheritance in His book. Thus, He has given news of glad tidings and eternal happiness for those who act upon these commands and punishment for those who do not:
"(After mentioning the laws of inheritance, Allah the Almighty says)These are the limits set by Allah. Whoever obeys Allah and His Messenger, He will admit him to gardens beneath which rivers flow, where he will live forever. That is a great success." (Surah An-Nisa, Ayah no. 13)
"Whoever disobeys Allah and His Messenger and transgresses the limits set by Him, He shall admit him to the Fire, where he will remain forever. For him there is a humiliating punishment." (Surah An-Nisa, Ayah no. 14)
A Muslim who holds the commands of Allah in high regard, believes in the accountability of the Hereafter, and is aware of the worldly and eternal punishment for depriving others of their rights, will never neglect these commands. Instead, he will make sure to give each rightful person their due share.
On the other hand, those Muslims who are engulfed in heedlessness and have made greed and desire their guiding principles, without considering the eternal and true life of the Hereafter, are the ones who usurp the rightful inheritance shares of their mothers or sisters, thereby committing a grave sin.