Imam Malik's Muwatta, Chapter: Faraid

Malik said, "The generally agreed on wayof doing things among us is that when there are no full siblings with them, half-siblings by the father take the position of full siblings. Their males are like the males of the full siblings, and their females are like their females except in the case where the half-siblings by the mother and the full siblings share, because they are not offspring of the mother who joins these." Malik said, "If there are both full siblings and half-siblings by the father and there is a male among the full siblings none of the half-siblings by the father have any inheritance. If there is one or more females in the full siblings and there is no male with them, the one full sister gets a half, and the half sister by the father gets a sixth, completing the two-thirds. If there is a male with the half-sisters by the father, they have no share. The people of fixed shares are given their shares and if there is something left after that it is divided between the half-siblings by the father. The male has the portion of two females. If there is nothing left over, they get nothing. If the full siblings consist of two or more females, they get two-thirds, and the half-sisters by the father get nothing with them unless there is a half-brother by the father with them. If there is a half-brother by the father with them, the people of fixed shares are given their shares and if there is something left over after that, it is divided between the half-siblings by the father. The male gets the portion of two females. If there is nothing left over, they get nothing. Half-siblings by the mother, full-siblings, and half-siblings by the father, each have a sixth (when they are onlyone). Two and more share a third. The male has the same portion as the female. They are in the same position in it."