What is the ruling on a husband asking his wife about how her father had intercourse with her mother during their own intercourse, in order to increase his arousal?

Filthy talk during intercourse is reprehensible. Talking about one's parents is even more reprehensible because it is insolence, an ugly act, and embarrassing to the wife. Therefore, the wife is not obliged to obey her husband in this, as obedience is only in what is good and lawful. He should be advised and his error pointed out. Sexual desire can be increased through other permissible means, such as foreplay with the wife.