What is the ruling on a colleague taking ten thousand [currency unit] in exchange for his mediation in the purchase of land, knowing that the commission is twenty thousand, which will be paid by the two buyers?

We understand from the question that your partner was asked by a real estate broker to find a buyer for a piece of land in exchange for a share of the commission. Your partner then wanted to buy it for himself and for both of you, and conceal this partnership from the broker to take a portion of the commission.

If this is the case, then there is no harm; because the broker's intention was to sell the land, and that has been achieved. His request to your partner to bring a customer in exchange for sharing the brokerage fee indicates his consent to a portion of it, and that has occurred.

What confirms the permissibility is your knowledge, as a partner, of the true situation, and that your colleague will take this portion for himself. The brokerage fee is only paid by the land buyer, and it is not permissible for the broker to take it except with the knowledge of the one who pays it.

And if brokers collaborate and do not stipulate a specific percentage for dividing their fee, then it is equally distributed among them.