When should an inheritance be divided upon the father's death, and what is the ruling on a mother preventing one of her sons from his inheritance due to a dispute with his wife?

The inheritance must be divided after the related rights and the deceased's bequests have been fulfilled and the necessary procedures completed. If any of the adult, sound heirs requests its division, then every rightful person must be given their due. There is no impediment to delaying the division for a valid reason with the consent of the adult, sound heirs. However, it is impermissible for the mother or anyone else to prevent an heir from their right with flimsy pretexts, because that is injustice and transgression against the limits of Allah. Allah the Almighty said: "These are the limits [set by] Allah, and whoever obeys Allah and His Messenger will be admitted by Him to gardens [in Paradise] under which rivers flow, abiding eternally therein; and that is the great attainment. But whoever disobeys Allah and His Messenger and transgresses His limits – He will put him into Fire, abiding eternally therein, and he will have a humiliating punishment."