The first post here brought to mind a rather "charming" painting at Olga's** web gallery:

Brulloff, Karl (Russian, 1799-1852)
In a Harem. By Allah's Order Underwear Should Be Changed Once a Year"
1850-1852. Oil on canvas
The Gallery of New Art, Milano, Italy.

Probably not too PC now, and not really that great a painting (in my estimation); but any research into the origin of such "laws" should investigate all historical contexts(?).

**I'll note that Olga's gallery features numerous advertising pop-ups, for those offended by them., and that this painting does show a graphic "changing of the underwear."

John