Is the money acquired by the questioner from the purchase of a plot of land, which represents the difference in price between what he informed his friend, the buyer, and what the landowner actually paid, in addition to his commission and the commissions of other brokers, without the knowledge of the buyer or the seller, permissible (halal) or forbidden (haram)? And if it is forbidden, what should he do?

It is permissible for a broker to take a fee for his work from either the seller or the buyer. He must be truthful and not collude to increase the price without the buyer's knowledge. If the agent's fee was not agreed upon, he is not permitted to take money from the principal without his knowledge; rather, he must return what he took unless the owner absolves him. As for what was paid to the female broker, if that is the prevailing custom, then there is no harm; otherwise, the principal must be informed. Writing a contract with an untrue price is considered a lie. It is obligatory to repent to Allah, inform the friend, and return the money to him.