Is an a brother entitled to request a sum of money in exchange for his unsolicited intervention in determining the sale price of orphans' land, and what is the meaning of "whoever attended the auction"?

If the brother did not stipulate a commission from the outset for his efforts in bringing the buyer and seller together, and he was not asked to do so, then he is not entitled to anything from the seller. However, if the buyer was the one who sought his mediation and requested it from him, and he is customarily entitled to a commission, then he can demand it from the buyer, not from the seller. Thus, the fee is owed by the one who sought his mediation, whether it was the seller or the buyer.