To acquire properties and to own goods, Islam places certain restrictions. The first of these being that it is Haram to win money or goods through games of chance or gambling. This is because the process of gambling involves taking another person's money without work involved, something that is quite contrary to a well functioning society. Gambling implies the possibility of easy money, money without work, and Islamic society necessarily requires every member of the community to be productive. The Qur'an is quite clear about the prohibition of gambling and all Muslims are urged to stand against games of chance.
Another restriction on the way one earns money is that no person is allowed to acquire goods or money through usury. Usury is considered unhealthy for the community since it, again, rewards individuals without the need for work. It encourages people to sit on their money and to collect rewards without actual labor, preying on those that are most needy in the community. Usury is destabilizing in that it creates social warfare and a hatred of the rich by the poor, an ill will that is in part justified because the rich get richer with no work on their part. God permits trading and business but forbids usury in all its forms in the Qur'an. In fact, God goes farther to say that the increase of wealth through usury is directly related to God's displeasure while money that is given instead in charity will attract the pleasure of God with the giver.
Islam is also quite clear about not allowing people to become rich by exploiting the weak. It goes on to say that taking advantage of the weaknesses of other human beings for one's own gain is an unacceptable way of gaining wealth, and completely against God's will. The Qur'an also goes farther and states that using the law to one's advantage in a fraudulent or devious way so that one may acquire another person's property is not lawful. Only trading and mutual consent between two parties is accepted under the rules of Islamic law. Something that is also considered a mortal sin is taking the property of orphans or of people at a disadvantage through fraudulent or exploitative means. The concept of justice in Islam recognizes an important property, that of Ihsan. Ihsan refers to giving more to those that are at a disadvantage so that they can stand at the same level as the rest of the community in all matters of life. Exploiting those that are at a disadvantage (the orphans, widows, people that are crippled or sick, those living in poverty, the elderly, etc.) is unlawful and goes quite clearly against the principles of Islam.