Is it permissible for the wife to travel alone to Qatar to help her married sister with childbirth, given that the wife's brother has covered the travel expenses? And does the sin of approval fall upon the husband or solely upon the wife if her travel is not permissible? And what should the husband do if he refuses her travel but she insists on it?

The majority of scholars hold the view that it is not permissible for a woman to travel without a mahram unless there is a necessity. However, some scholars have permitted it when there is no fear of fitna (temptation/strife), especially when traveling by plane. We advise traveling with the wife or one of her mahrams; otherwise, it is permissible to adopt the view of those who permit it, provided that safety measures are taken.