Ash-Shaikh Saalih al-Fawzaan, Rahimahullah, was asked the following question,
137 ما حكم البيع والشراء في العقار بالوكالات الشرعية؟
What is the ruling on buying and selling property through a legitimate real estate company?”
يجوز للإنسان أن يشتري لغيره عقارات بالوكالة عنه بأن يكون سمسارًا له ويأخذ في مقابل عمله أجرة من الموكل.
It is permissible for a person to purchase for other than himself property as a real estate agent on his behalf, such as him being a broker for him and he can receive a payment for his work from the one who initially delegated him”
The Reference: al-Mustataab min Fataawa al-Fawzaan
AbdulFattah bin Uthman
Shaikh Abdul-Muhsin Al-Abbaad was asked the following question:
What is the ruling on [working] in the field of real estate brokerage and taking a wage for that?
Brokerage for real estate or other than it is permissible. There is no harm in it.
How about for the one who will receive a wage from a number of parties?
In accordance to the agreement. If the payment is from the buyer or from this one or both, it is in accordance to what they agreed upon.
[Sharh Ibn Majah no. 74]
Faisal Ibn Abdul Qaadir Ibn Hassan
One can also see the dangers and flaws of usury outlined here by Shaikh Bin Baz rahimahullah in this research.