Is a husband entitled to prevent his wife from meeting her sister except in her brothers' house? Is the wife sinful if she disobeys that, and what are the cases in which a wife is permitted to disobey her husband?

The husband must help his wife obey Allah, and among the greatest acts of obedience is maintaining kinship ties. It is not permissible for a husband to prevent his wife from communicating with her relatives with whom ties must be maintained, except for a valid Shar'i (Islamic legal) reason. Thus, he may not prevent her from communicating with her sister merely because he dislikes her.

However, if the sister is not upright and there is a fear that she might corrupt the wife, then it is permissible to prevent her from communicating except for a minimal extent to fulfill the obligation of maintaining kinship ties.

If the sister is not upright, the wife must obey her husband by not meeting with her except in their brothers' house. If she is righteous, then the husband has no right to prevent her from doing so merely out of hatred.

It is not permissible for the wife to go out to meet her sister without her husband's permission.

A wife may disobey her husband's command in two cases: if he commands her to commit a sin against Allah, or if he commands her in a matter outside the affairs of the marriage contract.