Is a mother sinful for refusing to sell the inheritance and divide it among the children, which has caused animosity among them?

It is not permissible for the mother or any other heir to refuse to divide the inheritance after the heirs demand it. The mother's share of her husband's inheritance is one-eighth if he has a child, and it is not permissible for her to take more than that unless the heirs relinquish their rights. The matter must be presented to the Sharia courts for the division of the inheritance, and neither the mother nor anyone else has the right to object to this as long as some of the heirs request the division, because preventing someone who requests division is a forbidden injustice.