His statement, “Nor does he spend his wealth on what is unlawful”: for example, if—Allah forbid—he begins spending his wealth on intoxicants, then he is financially incompetent.
His statement, “or on that which brings no benefit”: likewise, if he spends his wealth on something of no benefit, such as a person who buys firecrackers and sets them off; or if he has banknotes, places one in his hand, and the wind carries it away, and he enjoys this, so he begins taking them out of the bag and holding them up in the air, letting them fly away—then he is financially incompetent, because he has spent his wealth on something of no benefit.
But is a person who spends his wealth on what is unlawful to be placed under legal interdiction? The apparent meaning of the author’s words is that he is to be placed under interdiction, because he spends his wealth on what harms him. But this is open to question, because people regard such a person as financially competent, even if he buys cigarettes with his money and smokes them, buys wine and drinks it, or buys narcotics and consumes them. Yet we may restrain him by another means: that is, by imprisoning him and flogging him. If he drinks wine, we flog him three times, and on the fourth occasion we execute him if nothing else deters him. The same applies to narcotics: the matter returns to the punishment prescribed in the Sacred Law.
However, to say that he is under legal interdiction when he is a man who is competent in buying and selling, but smokes cigarettes, is incorrect. Would we then say that he may not sell his house, may not sell his car, and may not buy bread for his children? We do not say this. Thus, we find that many people smoke cigarettes and thereby spend their wealth on what is unlawful, yet no judge has said that his sale of his house, his car, or the like is invalid. For in reality, he manages wealth competently; rather, he has gone astray in his religion and has become unconcerned about spending it on what Allah has forbidden him.