What is the ruling on a person mediating the purchase of a commodity for buyers, where he agrees with the seller to obtain a free commodity or at a reduced price in exchange for bringing the buyers, without the buyers' knowledge, or with their knowledge and acceptance?

If the owner of the sheep is satisfied with what the man requests in exchange for bringing buyers, then there is no harm in that, even if the owners of the sheep are unaware of the transaction, because the fee is taken from the owner of the sheep, not from the buyers. This act, known as brokerage (simsarah), is permissible in Islamic law. It involves a person searching for a buyer for a seller's merchandise, or for a seller for a buyer's need, and mediating between them to facilitate the sale. Many scholars have deemed it permissible.