Is it permissible to calculate the value of a house's rooftop at the same price as a rooftop sold 10 years ago, knowing that the youngest son was not satisfied with the sale, and the eldest son only paid half of the agreed-upon amount?

If the husband consented to sell his share to his brother for that amount, even out of shyness, then the sale is valid, and he has no right to demand an increase in price from his brother. However, if the brother knew that his brother sold it out of shyness and without full consent, then that is not permissible Islamically, based on the Almighty’s saying: "by mutual consent from you." This does not negate the validity of the sale, even if it is prohibited. The husband has done well by doing so to please his father and out of appreciation for his brother. He should anticipate good with the blessing of his dutifulness to his father, his ties of kinship with his brother, and his generosity in the sale.