Marrying more than one wife is a desirable thing - on condition that the man has the financial means and the physical ability to act with justice between his wives. This is because through plurality of wives, good is achieved, such as protecting the private parts of the women who he marries (from illegal sexual intercourse) and broadening of unity between the people, and increasing the number of births, as indicated by the Prophet: 'Marry loving, productive women.' It also contains many other benefits. As for a man marrying more than one wife out of pride and competitiveness, it is something which falls into the category of waste, which is not permitted.