Division of inheritance among a mother, father and four brothers

There are two views concerning this matter
among the scholars. 

The first view: 

This is the view of the majority, and is the
correct view among the Hanbali madhhab. This view states that if there
are two parents and a number of siblings, the mother gets one-sixth
and the rest goes to the father, because of the words of Allaah (interpretation
of the meaning): 

“… if the deceased left brothers
or (sisters), the mother has a sixth…” [al-Nisaa’
4:11] 

The general meaning
of the aayah indicates that the presence of siblings reduces the mother’s
share from one-third to one-sixth, whether they inherit or not. 

Al-Ramli, who was a Shaafa’i, said: “Know
that for a person to be able to prevent another person from inheriting
or reduce his share, he should himself be allowed to inherit. Whoever
does not inherit for a reason that may be mentioned later cannot prevent
anyone from inheriting altogether or decrease the amount he inherits,
except in a case such as when brothers are prevented from inheriting
by the presence of the father, but the mother’s share is reduced from
one-third to one-sixth because of their presence; and when her two children
are prevented from inheriting by the presence of their grandfather but
their presence reduces the mother’s share to one-sixth; and when there
are a husband, a full sister, a mother and a brother from the father’s
side, the brother has no share even though when combined with a full
sister this reduces the mother’s share to one-sixth.”

Nihaayat al-Muhtaaj Sharh al-Minhaaj, part 6,
p. 16 

The view
of the Maalikis is: “Everyone who cannot inherit anyway cannot prevent
an heir from inheriting or reduce his share” – except in five cases…
the second of which is: parents and siblings, where the mother’s share
is reduced to one-sixth and they (siblings) cannot inherit because they
are prevented from doing so by the father.

See Haashiyat al-‘Adawi, part 2, p. 388 

The second view:

That she gets one-third
along with the brothers whose share is reduced because of the presence
of the father. This is the view of some later scholars and it was the
view selected by Shaykh al-Islam Taqiy al-Deen Ibn Taymiyyah, but the
rest of the scholars differ from him. 

Their point is that the siblings do not reduce
the mother’s share to one-sixth unless they have the right to inherit
– so that they would benefit from reducing the mother’s share. The evidence
for this is the aayah (interpretation of the meaning): 

“… if the deceased left brothers or (sisters), the
mother has a sixth…” [al-Nisaa’ 4:11] 

where the father is not mentioned. The ruling
here refers to when the mother is on her own with siblings; after the
mother is given one-sixth, the rest is to be given to them. Among the
contemporary Hanbalis, this view was favoured by Shaykh ‘Abd al-Rahmaan
ibn Naasir al-Sa’di, when he said: “The correct view is that the brothers
who are prevented from inheriting or whose share is reduced do not prevent
the mother from inheriting one-third, because Allaah says (interpretation
of the meaning): ‘…if the deceased left brothers or (sisters)…’,
meaning heirs. As these brothers who are inheriting are not described
as being prevented from inheriting, so none of them can be prevented,
because the ruling on the division of inheritance is that the one who
does not inherit cannot prevent another from inheriting whether in whole
or in part. The reason for reducing the share of the mother is so that
they can have a share, but if they are not heirs they cannot prevent
anyone else from inheriting.  And Allaah knows best. 

See al-Tahqeeqaat al-Maradiyyah by
al-Fawzaan, p. 87-88 

Shaykh al-Islam Ibn Taymiyah (may Allaah have
mercy on him) said: 

Siblings cannot reduce the mother’s share
from one-third to one-sixth except if they are heirs, whose share is
not prevented by the presence of the father. In the case where there
are two parents or two brothers, the mother’s share is one third. The
presence of the grandfather prevents the brothers from inheriting, thus
the brothers could not reduce the share of the mother because they themselves
are prevented from inheriting, according to scholarly consensus. The
same applies with regard to parents or the father. This was narrated
from Imaam Ahmad and was the view selected by some of his companions,
and this was the view of Abu Bakr and others among the Sahaabah (may
Allaah be pleased with them).

See al-Fataawa al-Kubra, part 5, p. 446

Since there
is scholarly dispute on this matter, you should refer to the qaadi (Muslim
judge) in your country, because the ruling of the judge will dispel
the differences.

And Allaah knows best.