Malik said, "The generally agreed on way of doing things among usabout which there is no dispute and what I have seen the people ofknowledge in our city doing is that when a father inherits from a sonor a daughter and the deceased leaves children, or grandchildrenthrough a son, the father has a fixed share of one sixth. If thedeceased does leave any children or male grandchildren through a son,the apportioning begins with those with whom the father shares in thefixed shares. They are given their fixed shares. If a sixth or more isleft over, the sixth and what is above it is given to the father, andif there is less than a sixth left, the father is given his sixth as afixed share, (i.e. the other shares are adjusted.)"Theinheritance of a mother from her child, if her son or daughter diesand leaves children or male or female grandchildren through a son, orleaves two or more full or half siblings is a sixth. If the deceaseddoes not leave any children or grandchildren through a son, or two ormore siblings, the mother has a whole third except in two cases. Oneof them is if a man dies and leaves a wife and both parents. The wifehas a fourth, the mother a third of what remains, (which is a fourthof the capital). The other is if a wife dies and leaves a husband andboth parents. The husband gets half, and the mother a third of whatremains, (which is a sixth of the capital). That is because Allah, theBlessed, the Exalted, says in His Book, 'His two parents each have asixth of what he leaves if he has children. If he does not havechildren, and his parents inherit from him, his mother has a third. Ifhe has siblings, the mother has a sixth.' (Sura 4 ayat 11). The sunnais that the siblings be two or more."
USC-MSA web (English) reference: Book 27, Hadith 0