To what extent should a wife obey her husband who forbids her from observing voluntary fasts due to his fear for her health?

A woman is not permitted to observe a voluntary fast while her husband is present, except with his permission, due to the hadith: "It is not lawful for a woman to fast while her husband is present except with his permission." However, if the husband is traveling, or if his prohibition of fasting is out of compassion and not due to his need, then she is not obligated to obey him. The prohibition against observing a voluntary fast without the husband's permission is due to his right to enjoy her. If the husband is ill and unable to enjoy her, then the wife may fast without his permission. Obedience to the husband is obligatory in what is good and lawful, and her good devotion to him is among the reasons for her entry into Paradise.