Hadith 655
۞
"If a man dies and leaves behind both his parents, the mother receives one-third of the inheritance, and the father receives two-thirds.
If he leaves behind his parents and a brother or a sister, the mother still receives one-third, and the father receives two-thirds.
However, if he leaves behind his parents and either a brother and two sisters, two brothers, or even four sisters from either the father's side or both the father's and mother's side, then the mother receives only one-sixth, and the remainder goes to the father.
This is based on the words of Allah (swt), the Almighty:
'But if he had brothers and sisters, then for his mother is one-sixth.' (Surah An-Nisa 4:11)
They (the siblings) reduce the mother's share from one-third to one-sixth because they are dependent on the father for their living expenses; thus, they block (reduce) her share without inheriting themselves.
However, if he leaves behind his parents and siblings from the mother's side (maternal siblings), regardless of their number, they neither reduce the mother's share from one-third nor do they inherit."
إِذَا مَاتَ الرَّجُلُ وَ تَرَكَ أَبَوَيْهِ فَلِأُمِّهِ الثُّلُثُ وَ لِلْأَبِ الثُّلُثَانِ فَإِنْ تَرَكَ أَبَوَيْهِ وَ أَخاً أَوْ أُخْتاً فَلِلْأُمِّ الثُّلُثُ وَ لِلْأَبِ الثُّلُثَانِ فَإِنْ تَرَكَ أَبَوَيْهِ وَ أَخاً وَ أُخْتَيْنِ أَوْ أَخَوَيْنِ أَوْ أَرْبَعَ أَخَوَاتٍ لِأَبٍ أَوْ لِأَبٍ وَ أُمٍّ فَلِلْأُمِّ السُّدُسُ وَ مَا بَقِيَ فَلِلْأَبِ لِقَوْلِ اللَّهِ عَزَّ وَ جَلَّ فَإِنْ كانَ لَهُ إِخْوَةٌ يَعْنِي إِخْوَةً لِأَبٍ أَوْ لِأَبٍ وَ أُمٍّ فَلِأُمِّهِ السُّدُسُ وَ إِنَّمَا حَجَبُوا الْأُمَّ عَنِ الثُّلُثِ لِأَنَّهُمْ فِي عِيَالِ الْأَبِ وَ عَلَيْهِ نَفَقَتُهُمْ فَيَحْجُبُونَ وَ لَا يَرِثُونَ وَ مَتَى تَرَكَ أَبَوَيْهِ وَ إِخْوَةً وَ أَخَوَاتٍ لِأُمٍّ مَا بَلَغُوا لَمْ يَحْجُبُوا الْأُمَّ عَنِ الثُّلُثِ وَ لَمْ يَرِثُوا.