1021 - Issue: He said: "If there are fixed-share heirs (ashab al-fara'id) along with the grandfather, brothers, and sisters, the fixed-share heirs are given their shares. Then, that which remains is considered. If division is better for the grandfather than a third of what remains and a sixth of the entire estate, he is given the division. If a third of what remains is better for him than the division and a sixth of the entire estate, he is given a third of what remains. If a sixth of the entire estate is more favorable to him than the division and a third of what remains, he is given a sixth of the entire estate."

As for the fact that he does not receive less than a sixth of the entire estate, it is because he does not receive less than that when there are children, who are more entitled [to inherit] than them, so with others, it is more appropriate. As for giving him a third of the remainder when it is more favorable to him, it is because he has a third when there are no fixed shares; therefore, what is taken by the fixed share is as if it has departed from the estate, so a third of the remainder becomes equivalent to a third of the entire estate. As for the division, it is for him when there are no fixed shares, so it is the same when they are present. According to this, whenever the brothers exceed two, or those who equal them from among the females, he has no portion in the division. Whenever they are fewer than that, he has no portion in a third of the remainder. Whenever the fixed shares exceed half, he has no portion in a third of the remainder. If they are less than half, he has no portion in the sixth. If the fixed share is exactly half, the sixth and a third of the remainder are equal. If the brothers are two, a third of the remainder and the division are equal.

1022 - Issue: He said: "The grandfather shall never be reduced below a sixth of the entire estate, or his allotment if the shares increase."

This is the opinion of the generality of the scholars, except that it was narrated from al-Sha'bi that he said: Ibn Abbas wrote to Ali regarding six brothers and a grandfather. He wrote back to him: "Make the grandfather the seventh of them, and erase this letter of mine."