Is it permissible for a man to sell something that he owns to one of his sons, knowing that some of them are able to make the purchase whilst others do not have anything and cannot make the purchase?
Praise be to Allaah.
It is permissible for a man to sell some of his property to one of his sons, if he (the son) is able to make the purchase, and he should deal with him as he would deal with a stranger. He should not give him any preferential treatment that would indicate that he favours him over his siblings.
From Fataawaa al-Lajnah al-Daa’imah, part 13/15