If a man dies and leaves behind a father and children, how is the estate divided?
Question

                If I work and acquire capital, then Allaah causes me to die when my father is still living, does my estate go to my father or to my children?.
Praise be to Allah.If a man 
    dies and he has a father who is still living and male children, or male and 
    female children, then the father gets one-sixth of the estate, the wife gets 
    one-eighth if he has a wife, then the rest is given to the children, with 
    each male getting the share of two females. 
But if the 
    children are females only, one daughter or more, then the wife takes 
    one-eighth, if there is a wife then the daughter or daughters take what 
    Allaah has allocated to them: half for one daughter, and two-thirds for two 
    or more daughters. Then in addition to the one-sixth, the father takes 
    whatever is left of the estate after the wife and daughters take their 
    shares. 
This is 
    indicated by the words of Allaah (interpretation of the meaning): 
“Allaah 
    commands you as regards your children’s (inheritance): to the male, a 
    portion equal to that of two females; if (there are) only daughters, two or 
    more, their share is two-thirds of the inheritance; if only one, her share 
    is a half. For parents, a sixth share of inheritance to each if the deceased 
    left children”
[al-Nisa’ 
    4:11]
Ibn Qudaamah 
    (may Allaah have mercy on him) said: 
There are 
    three scenarios with regard to inheritance for the father: 
1 – He 
    inherits a stipulated share, if there is a son or grandson. He gets no more 
    than one-sixth and the rest goes to the son and those who are with him. We 
    do not know of any difference of scholarly opinion concerning this. That is 
    because Allaah says (interpretation of the meaning): 
“For 
    parents, a sixth share of inheritance to each if the deceased left children”
[al-Nisa’ 
    4:11]
2 – The 
    father inherits by virtue of kinship on the male side only. This applies if 
    there is no child (child includes both male and female). In this case he 
    takes the wealth if he is the only heir. If there is another heir who is 
    entitled to a stipulated share, such as a wife, mother or grandmother, then 
    those who are entitled to stipulated shares are given their shares, and the 
    rest of the wealth goes to him, because Allaah says (interpretation of the 
    meaning): 
“if no 
    children, and the parents are the (only) heirs, the mother has a third”
[al-Nisa’ 
    4:11]
So the 
    inheritance is given to both parents, then the mother is allocated 
    one-third, therefore the rest is for the father. 
3 – Where 
    both the stipulated share and the kinship on the male side are combined. 
    This is when there are female children, or a son of his son (i.e., along 
    with the daughter or daughter of his son). In this case, the father gets 
    one-sixth, because Allaah says (interpretation of the meaning): 
“a sixth 
    share of inheritance to each if the deceased left children”
[al-Nisa’ 
    4:11]
The father 
    gets one-sixth if there is a daughter, according to scholarly consensus, 
    then he takes whatever is left by virtue of kinship on the male side, 
    because of the report narrated by Ibn Abbaas who said: The Messenger of 
    Allaah  (peace and blessings of Allaah be upon him) said: “Give the 
    shares of inheritance to those who are entitled to them, and whatever is 
    left is for the closest male relatives.” Agreed upon. 
The father 
    is the closest male relative after a son and grandson, and the scholars are 
    agreed upon all of this. There is no difference of opinion concerning it as 
    far as we know, praise be to Allaah. End quote from al-Mughni 
    (6/169). 
And Allaah 
    knows best.