it is valid; otherwise, it is void. This is the school of Abu Hanifa. The statement regarding it is the same as the statement regarding the sale, as previously mentioned.

Section: The Judge said: If a man says to another: "Purchase for me food using the debt you owe me," it is not valid. If he says: "Borrow a thousand [dirhams] for me from your wealth in exchange for a kurr (of grain). He did so; it is valid; because it is not permissible for a person to purchase with his own wealth what another already owns. If he says: "Purchase for me on your own liability," or says: "Borrow a thousand [dirhams] for me in exchange for a kurr of grain, and pay the price for me from your wealth, or from the debt that I have against you," it is valid; because when he purchases on his liability, the purchase is secured for the principal and the price is his liability. Thus, when he pays it from the debt he owes, he has paid the debt to the one whom the creditor commanded him to pay. And if he pays it from his own wealth toward the debt of the loan he owes, it becomes a loan against him.

Section: An agent does not possess the authority to act except in accordance with what his principal’s permission dictates, whether by way of explicit verbal command or by way of custom; for his action is based on the permission, so it is restricted to what was permitted. Permission is known sometimes by words and sometimes by custom. If he appoints a man to act at a specified time, he does not possess the authority to act before it or after it; because his permission, either verbally or by custom, did not encompass it; for he may prefer the action at the time of need for it, and not otherwise. This is why when Allah the Exalted appointed a time for His worship, it was not permissible to perform it before it or after it. Therefore, if he says to him: "Sell my garment tomorrow," it is not permissible for him to sell it today or the day after tomorrow. And if he specifies a place for him, and a purpose is attached to it, such as if he orders him to sell his garment in a specific market, and that market is known for the quality of the currency, the abundance of the price, or its legitimacy, or the goodness of its people, or due to a friendship between the principal and them, the permission is restricted to it; because he has specified a matter in which he has a purpose, so it is not permissible to bypass it. And if it and another are equal in terms of purpose, the permission is not restricted to it, and it is permissible for him to sell in another; due to its equivalence.