What is the ruling on a competition that leads to the winner controlling sexual intercourse whenever he wishes, and failure to execute his command results in the payment of a sum of money?

This competition is impermissible, and its condition is void. It is obligatory for a wife to obey her husband in lawful enjoyment with her, and it is not permissible for her to refuse except for a valid excuse such as illness, menstruation, an obligatory fast, or harm she would incur from intercourse. And the husband has the right to enjoy his wife at any time and in any manner, as long as it does not harm her or distract her from obligatory duties.