They ask you for a ruling. Say, “God gives you a ruling concerning the person who has neither parents nor children.” If a man dies, and leaves no children, and he had a sister, she receives one-half of what he leaves. And he inherits from her if she leaves no children. But if there are two sisters, they receive two-thirds of what he leaves. If the siblings are men and women, the male receives the share of two females.” God makes things clear for you, lest you err. God is Aware of everything.

The Holy Quran · An-Nisaa (The Women) · 4:176