
Yeah, no. Forget the history of soap for a moment, and the fact that the Celts were using it long before Islam was even a thing. The title of the painting is "The Bath" by Jean-Léon Gérôme. It depicts a woman from an Ottoman sultan's harem being washed by a servant. Gérôme was well-known for these sorts of scenes, based on his travels throughout the Middle East and Bursa in Turkey in particular, where he was able to see and paint these particular harem bath-house scenes. There's no "Moor" in this painting, and the servant girl is certainly not "showing the [harem girl] how to bathe".