Pure cedar oil is basically a type of essential oil. It is not a triglyceride (the kind of fat that saponifies). Cedar oil meant for furniture care is usually some small amount of real cedar oil mixed with other stuff, including mineral oil which doesn't saponify. I would definitely not use the furniture oil for soaping. Pure cedar oil could be used for scent, but I'd be careful with it in soap or anything intended for the skin -- it could be an irritant for skin.