, an executor, and an administrator derive their authority through the owner’s specific appointment, whereas a guardian’s authority derives from the Sacred Law.

Accordingly, if one person appoints another as his agent to sell something, and the agent sells it, the sale is valid, even though the agent is not the owner; he acts in the owner’s stead. However, the agent must act in the manner he considers most beneficial. Thus, if the value of an item is increasing, he must not sell it until the increase has ended. This differs from one who disposes of his own property, for he may sell an item for less than its value. The difference is that one acting on behalf of another must seek what is most advantageous, whereas one acting for himself may dispose of it as he wishes.

For example, if you give this man a recorder to sell, and people continue raising their bids for it until it reaches one hundred or two hundred, he may not sell it while the bids are still increasing, until the price has stabilized. But if its owner sells it for one hundred riyals when it is worth two hundred, this is permissible, because the owner is disposing of his own property, whereas the other is disposing of another’s property.

Consider this principle—that one acting on behalf of another must seek what is most advantageous—even in acts of worship. An imam must lead the people in prayer according to the sunnah, whereas another person may pray as he wishes. The Prophet (peace and blessings be upon him) said: “When one of you leads the people in prayer, let him be brief; but when he prays by himself, let him lengthen it as he wishes.” (1)

“If he sells another person’s property, or purchases something with a specific asset belonging to that person without his permission, it is invalid. But if he purchases something for him on his own liability without his permission, and does not identify him in the contract, it becomes valid for him upon ratification; otherwise, the purchaser is bound by it and takes ownership of it ...”

His statement, “If he sells another person’s property,” means that the sale is invalid, because he is not the owner and the condition of ownership is absent. Thus, if he sells his father’s property or his son’s property, the sale is invalid.