Rules regarding purchase and sale
2059. It is recommended for a business man to learn the rules of daily transactions. In fact, if due to ignorance, he may necessarily contradict the laws of Shariah, then it is obligatory upon him to learn. Imam Ja'far Sadiq (A.S.) is reported to have said: "A person who wishes to engage in business, should learn its rules and laws, and if he makes any transaction without learning them, he may suffer because of entering into a void or doubtful transactions".
2060. If a person is not aware, because of ignorance about the relevant laws, whether the transaction made by him is valid or void, he cannot have any discretion over the property which he has acquired, unless he knows that the other party has no objection to it. In any case, the transaction remains void.
2061. If a person does not possess any wealth, and it is obligatory on him to maintain his dependents, like, his wife and children, he should start earning. Moreover, to earn is recommended for Mustahab acts like providing better means of livelihood to one's family, and helping the poor persons.