Is it permissible for a parent to let their married sons live in their own homes or apartments free of charge and without compensation to the rest of their siblings? that case If sons are government employees and are able to pay rent regularly and their married sisters live in rented houses with their spouses.
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All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the father singles out the married sons by providing them with dwelling in his home free of charge, while they do not need it and are able to pay the rent, then this is not permissible, because gifting some children without a sound justified reason [without gifting all other children] is not permissible according to our preponderant view in Islamweb. However, if he singles them out because of their need and not because of favoring them, like if they cannot pay the rent with their salaries except if they restrain themselves in other living expenses, then, in this case, there is no harm on their father to single them out with the dwelling.

Ibn Qudaamah said:

"If the parent favors some of his children over the others with gifts for a valid reason such as a need, disability, chronic illness, blindness, having a bigger family and greater responsibilities, preoccupation with seeking knowledge or similar virtues, or if he denies some of his children gifts due to their dissoluteness, practicing religious innovations, or because they would spend it on disobeying Allah, then the permissibility in this regard was reported on the authority of (Imam) Ahmad. He said regarding favoring some of the children with endowments, 'There is no harm if it is for a need, and it is disliked if it is mere favoring.' A gift bears the same meaning of an endowment." [End of quote]

For more benefit, please refer to Fatwa 334813.

Allah knows best.