Giving the grandson a gift and not the sons

Q: My father is about 75 years old. He had an old adobe house in a distinct location. I pulled it down to rebuild it with concrete from my money. I rented the house and I still repay some of my debts from the value of the rent. It should be noted that I did not take loans from the Land Development Bank. My father wants to register this house in the name of one of my children who is seven years old. It should be noted that I have other five sisters. One of them is older than me and the rest of them are younger than me. I have sustained my father and my mother for fifteen years now. My father felt ill and I took him outside the Kingdom of Saudi Arabia for treatment. My son is the only male grandson in the family. My question now is: Is it permissible for my father (Part No. 16; Page No. 206) to give this house to my son? It should be noted that my five sisters are married and my father assumed the expenses of their marriage. My parents live with me in my house, so the rest of my family do not oppose my father's registering of this house in my son's name and giving him the right to use it. I promised my father that in case my sisters left the house for my son, I will build another house for them from my money to free my father from responsibility. I would like to have your advice in this regard. Is my father or any of us committing a sin this way?

A: Considering what you have mentioned: 1- That your father will give the house to your son, even if there is no need for this at the present time; 2- That you promised your father if he gives the house to your son that you will build another house for your sisters from your own money; 3- That you have five married sisters; and 4- That you have built your father's house which he intends to give to your son. All this indicates that your father wants to give you alone the house and deprive your sisters of it. Your son is used as a cover for your practice of injustice. Therefore, it is not permissible for your father to give the house to your son according to the saying of the Prophet (peace be upon him): Be afraid of Allah, and be just to your children. As regards what you mentioned about your spending on your father's house, (Part No. 16; Page No. 207) if you did it out of kindness to your father, Allah will reward you for this. However, you should not take back what you spent on your father. If you intended to take it back from your father, it is permissible for you to do so but it is better not to. You should not regard whatever you spend on your father as too much, because Allah (Glorified and Exalted be He) will reward you much more than you could expect in case you are sincere to Him (Glorified and Exalted be He). May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.