“I once said to abu ‘ Abd Allah (a.s.), a man traveled and then came back with a great deal of assets and we did not know if he had earned it in a lawful or unlawful ways. He (the Imam) said, ‘If such is the case, look how he spends it. If he spends in ways that he is not supposed to spend or is of the sinful ways it then is from unlawful ways.’”