Is there evidence that specifies the rate of profit for a person in his buying and selling? Or is he free to earn whatever he wishes and profit as much as he wishes?

Al-Huwaini: Is there evidence for specifying the rate of profit... or does a person earn whatever he wishes and profit as much as he wishes?

The Shaykh: There is no evidence in the Shari'ah that mandates a specific rate, such as one-third, as is mentioned in some books of Islamic jurisprudence by some later authors. Rather, this is an opinion and independent legal reasoning, and there is no evidence for it. However, it is of the utmost wisdom that the Shari'ah left the issue of determining profit open and did not restrict it; for that is in accordance with wisdom, because a commodity that sells in large quantities cannot have the same profit margin as a commodity that sells in small quantities. Therefore, supply and demand are what determine the rate of profit. But what is obligatory for the Muslim to adhere to is to avoid excessive uncertainty in a contract, concealment of a defect in a chain, and deceiving customers. For example, saying, "You did not pay the capital for this commodity," or "What you are paying, others have paid more than that." All of this is a means to lure more profit and greater gain from this customer through such false claims. This is not permissible. However, if you say a brief word: "The price of this commodity is such and such," and the profit may be double the capital, there is no objection. Even if you were greedy, you will regret it later when the man goes elsewhere and buys this commodity for less than what you mentioned. At that time, your greed will return harm to yourself, and customers will be less likely to patronize you after they realize that you are demanding exorbitant prices.
Yes.