There is a prophetical statement that prophet Muhammed knew that his son-in-law (Ali) had the intention to marry another woman in addition to Muhammed's daughter (Fatma). When he knew that, prophet Muhammed got angry and he said he would not agree on that. Why did not prophet Muhammed agree on that although he himself was married to NINE women at the time? Some people say that the reason was that the new bride that Ali wanted to marry was the daughter of Muhammed's enemy (Abu Gahl), but I am still confused because many of prophet Muhammed's wives were daugters of his enemies as well (Abu Sofyan as well as most Jewish tribes)