If he lets one of his sons live in an apartment for free, is he obliged to treat the rest of his sons equally?

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Check below answers in case you are looking for other related questions:
Does a mother have to be fair in giving gifts to her children?
Ruling on differentiating between children in gift-giving

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Does a mother have to be fair in giving gifts to her children?
Ruling on differentiating between children in gift-giving

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