Who is permissible to serve as the wife's attendant (Khadim)?

Primary text

The attendant must be someone to whom looking upon the wife is permissible due to the constant proximity involved in service. This means the servant must either be a woman or a male relative (Dhu Rahm Mahram). The sound opinion permits a servant from the People of the Book because their employment is permissible, and looking upon them is generally permitted.