What is the ruling regarding a wife saying to her husband, "I am forbidden to you as my mother and sister are forbidden to me," intending prohibition at a time of anger? And does she owe an expiation of Dhihar by fasting for two consecutive months or feeding 60 poor people? And how does a woman perform it during menstruation?

It is not permissible for a woman to forbid herself from that which Allah has made lawful for her. If she does so, she must repent and offer expiation (kaffarah) similar to that for breaking an oath: feeding ten poor people, or clothing them, or freeing a slave. If she cannot find these, then fasting for three days. It is permissible to appoint someone else to perform the expiation on her behalf.