Quran 4:12

وَلَڪُمۡ نِصۡفُ مَا تَرَكَ أَزۡوَٲجُڪُمۡ إِن لَّمۡ يَكُن لَّهُنَّ وَلَدٌ۬‌ۚ فَإِن ڪَانَ لَهُنَّ وَلَدٌ۬ فَلَڪُمُ ٱلرُّبُعُ مِمَّا تَرَڪۡنَ‌ۚ مِنۢ بَعۡدِ وَصِيَّةٍ۬ يُوصِينَ بِهَآ أَوۡ دَيۡنٍ۬‌ۚ وَلَهُنَّ ٱلرُّبُعُ مِمَّا تَرَكۡتُمۡ إِن لَّمۡ يَڪُن لَّكُمۡ وَلَدٌ۬‌ۚ فَإِن ڪَانَ لَڪُمۡ وَلَدٌ۬ فَلَهُنَّ ٱلثُّمُنُ مِمَّا تَرَڪۡتُم‌ۚ مِّنۢ بَعۡدِ وَصِيَّةٍ۬ تُوصُونَ بِهَآ أَوۡ دَيۡنٍ۬‌ۗ وَإِن كَانَ رَجُلٌ۬ يُورَثُ ڪَلَـٰلَةً أَوِ ٱمۡرَأَةٌ۬ وَلَهُ ۥۤ أَخٌ أَوۡ أُخۡتٌ۬ فَلِكُلِّ وَٲحِدٍ۬ مِّنۡهُمَا ٱلسُّدُسُ‌ۚ فَإِن ڪَانُوٓاْ أَڪۡثَرَ مِن ذَٲلِكَ فَهُمۡ شُرَڪَآءُ فِى ٱلثُّلُثِ‌ۚ مِنۢ بَعۡدِ وَصِيَّةٍ۬ يُوصَىٰ بِہَآ أَوۡ دَيۡنٍ غَيۡرَ مُضَآرٍّ۬‌ۚ وَصِيَّةً۬ مِّنَ ٱللهِ‌ۗ وَٱللَّهُ عَلِيمٌ حَلِيمٌ۬ ١٢

You get half of what your wives leave behind, if they had no children. If they had children, you get one-fourth of what they leave. All this, after fulfilling any will they had left, and after paying off all debts. They get one-fourth of what you leave behind, if you had no children. If you had children, they get one-eighth of what you bequeath. All this, after fulfilling any will you had left, and after paying off all debts. If the deceased man or woman was a loner, and leaves two siblings, male or female, each of them gets one-sixth of the inheritance. If there are more siblings, then they equally share one-third of the inheritance. All this, after fulfilling any will, and after paying off all debts, so that no one is hurt. This is a will decreed by ALLAH. ALLAH is Omniscient, Clement.