What is the ruling regarding the eldest brother gifting all his possessions to his wife in order to deprive his siblings of their inheritance? And what is the punishment for that in religion?

It is permissible for a brother to register his properties in his wife's name and gift them to her, but he is not allowed to do so with the intention of disinheriting some heirs, as this is a forbidden stratagem. If his intention in registering them in his wife's name is to disinherit his siblings, then he is sinful. If he registered them for her as a bequest effective after his death, then it is a bequest to an heir, which is not enforceable without the consent of the other heirs. If he registered them for her during his health, and she did not take possession of them before his death or his life-threatening illness, then the gift is void. However, if he relinquishes control over them and his wife takes possession of them as an owner, then the properties become hers, and the husband is sinful by his intention.