The Gift to the Creditor as Riba

Question: Hasan and Ali, who are friends and colleagues, agreed to finance the construction of a residential building. Ali would finance the project to the extent of 300,000 riyals, on the condition that Hasan would repay this amount to Ali annually from his own resources. Hasan voluntarily promised Ali, without any condition or restriction, to give him the rent of three apartments in the building as a gift. Then the project was completed, and the amount increased from 300,000 riyals to 400,000 riyals.
Is the amount that Hasan, the debtor, committed to pay to Ali, the creditor, from the rent of the three apartments, voluntarily and as a gift, lawful, or does it contain some element of riba?

Answer: What appears from the situation of the two individuals is that this money which Hasan pays to Ali is in exchange for his being given time and delay in his share of the building's expenses. Even if they called it voluntary and a gift, Allah knows what is in hearts. This money was not paid for the sake of friendship or kinship; rather, it was paid for this work that Ali did, which is that he spent on the building until it was completed. Then the matter between them would be as they stipulated, but Hasan would give him this gift in exchange for this work, as he says.
The point is: this appears to be riba; because he only lent to him for the sake of this gift, and it is not a gift in reality. It is merely a benefit for delaying and giving him time. And Allah knows best.