Just to support Tanveer's point in 2006's discussion. There was a claim if there is a verse forbidding marrying 2 sister at the same time then polygamy should be ok, because if polygamy is forbidden then what is the logic of mentioning 2 sisters case. Good question. Until two cerses about alcohol; alcohol is evil, and don't practice salat while drunken. If alcohol is forbidden what is the point of mentioning don't salat with alcohol? I don't know. But it is there. Kust like 2 sisters.