Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa., – Volume 13, Page 15, Question 1 of Fatwa No.4153
Question: Is it permissible for a man to sell something from his possessions to some of his children, knowing that some of them are able to purchase, whilst others do not have anything and are unable to purchase?
Response: It is permissible for a man to sell some of his possessions to some of his children, if he (the child) is able to purchase, and he should deal with him as he would deal with a stranger; He should not give him any preferential treatment indicating that he favours him over his siblings.
And with Allaah lies all success and may Allaah send prayers and salutations upon our Prophet ﷺ and his family and his companions.