1. No fraud or deceit, the Prophet (pbuh) is reported to have said, “ When a sale is held, say, “There’s no cheating” (Al-Bukhari).
2. Sellers must avoid making too many oaths when selling merchandise. The Prophet (pbuh) is reported to have said, “Be careful of excessive oaths in a sale. Though it finds markets, it reduces abundance” (Muslim).
3. Mutual consent is necessary. The Prophet (pbuh) is reported to have said, “The sale is complete when the two parties involved depart with mutual consent” (Al-Bukhari).
4. Be strict in regard to weights and measures. The Prophet (pbuh) is reported to have said, “When people cheat in weight and measures, their provision is cut off from them” (Al-Muwatta). He told the owners of measures and weights, “You have been entrusted with affairs over which some nations before you were destroyed” (Al-Tirmidhi).
5. The Prophet forbade monopolies. “Whoever monopolizes is a sinner” (Abu Dawud).
6. Free enterprise, the price of the commodities should not be fixed unless there is a situation of crisis or extreme necessity.
7. Hoarding merchandise in order to increase the prices is forbidden.
8. Transaction of haram items, such as intoxicants, are forbidden.
The Prophet’s general advice to all people was, “What is lawful is clear and what is unlawful is clear, but between them are certain doubtful things which many people do not recognize. He who guards against the doubtful things keep his religion and his honour blameless, but he who falls into doubtful things falls into what is unlawful, just as a shepherd who pastures his flocks round a sanctuary will soon pasture them in it. Every king has a sanctuary, and God’s sanctuary is the things he had declared unlawful” (Al-Bukhari).