Ruling on taking a fee for agency in sales

The question: His second question says: I travel to Kuwait, and a person comes to me and says: Buy me a specific watch from the Kuwait market, and we agree that he will give me a profit and extra fees of three percent over the invoice. Is this permissible in the Shari'ah?
The answer: If he agrees with him on a fee of three percent for his effort in buying the watch, there is nothing wrong with it. If he agrees with him that he will buy the watch as his agent, but he gives him three percent or five percent in return for his effort, there is no blame on him. However, for example, if he sells to him, buying it and then selling it to him when it is not in his ownership, no, he does not sell to him the watch that is not in his ownership; rather, he is an agent who buys the watch for him and gives it to him, but he has a fee from the perspective of agency, and there is nothing wrong with that. And he does not have the right to sell him the watches after he has bought them. Yes...