Is eligibility for commission restricted to whoever exerted effort in reconciling the seller and the buyer until the sale was concluded, or merely to whoever pointed to the land or its owner?

First: It is permissible to work in brokerage if the broker adheres to the Sharia (definition) guidelines, due to the benefit it provides to both parties. The "Mudawwana" (Maliki legal text) states the permissibility of a broker's fee.

Second: If more than one person participates in brokering a single item, the situations are as follows: 1. If there is a partnership, a condition, or an established custom between them, they are bound by their condition, based on the Almighty's saying: ﴿O YOU WHO HAVE BELIEVED, FULFILL [YOUR] CONTRACTS﴾ and the Prophet's (PBUH) saying: «MUSLIMS ARE BOUND BY THEIR CONDITIONS». 2. If there are regulations organized by the state, then they are according to what is stipulated therein. 3. If the second broker benefits from the work of the first, the principle is that the fee should be shared between them, and they refer to the prevailing custom in the market if there is no condition between them. 4. If there is an agreement or custom of exchanging information for free, then the first broker is not entitled to any part of the brokerage fee. 5. Your relationship is with the broker who gave you the information or directly assisted you, and he is the one who communicates with those who benefited from them. 6. You are not obliged to pay anything to publicly available websites, as it is customary for them to take their fee from the advertiser.