Does the mother's share (one-sixth) only become excluded when there are three brothers present?
General Chapter
Al-Mughni
Book of Inheritance Shares (Farā'id)
Primary text
The mother is only excluded from inheriting her one-sixth share when there are three brothers present. This is a point of difference with Ibn Abbas.
Supporting text
Ibn Abbas held a different opinion regarding the specific number of brothers required to exclude the mother from her fractional share.