How is the inheritance to be divided among the mentioned heirs, and does the mother's retraction of her statement "I don't want anything; all my inheritance goes to her children" affect her share of the inheritance?

First, the debts owed by the deceased must be paid before the inheritance is distributed, because debt takes precedence over the heirs' right, as Allah Almighty says: "after any bequest he may have made or any debt." After the debt is paid, the remainder is divided among the heirs. The mother receives one-sixth due to the presence of a lineal descendant, and the wife receives one-eighth, also due to the presence of a lineal descendant. The remaining portion is for the sons and the daughter by way of ta'sib (residuary heirship), with the male receiving the share of two females. The full brother does not inherit in the presence of a son. The inheritance is divided into 168 shares: the mother receives 28 shares, the wife receives 21 shares, each son receives 34 shares, and the daughter receives 17 shares. The mother's statement that she does not want anything is considered a gift (hiba), and she has the right to retract it unless the children have taken possession of her share.