Does the brother inherit the remainder of his deceased brother's wealth if the deceased bequeathed a portion of his wealth to his nephew during his illness, and the deceased had no surviving descendants?

If the nephew establishes proof that his uncle gifted him the money during his lifetime and during an illness that was not life-threatening, then the money belongs to him. However, if he does not establish proof, then the money is an inheritance of the deceased, which his brother inherits. And if he establishes proof that the gift was made during a life-threatening illness, then the nephew receives one-third of the inheritance, because it takes the ruling of a bequest.