Is it permissible for a mother to ask her son for more money for savings or for associations, despite her financial sufficiency and the son's commitment to providing for his unmarried sister?

A husband is not obligated to give his mother money she does not need. However, if he donates it without harming himself or falling short in providing for his wife and children as is obligatory, then it is a righteous deed, one of the best acts of piety and maintaining kinship ties. It is hoped that it will bring blessings and goodness to them in their religious and worldly affairs, for the Prophet, peace and blessings be upon him, said: "Whoever wishes that his provision be expanded for him and his life span be extended, let him maintain his ties of kinship."