What are the conditions for a valid will and for its nullification?

A will is valid if it is made by a free, discerning person who owns what he bequeathed, and to someone who is capable of owning it. It is not valid for an heir unless the other heirs permit it, nor for more than a third of the estate unless they agree; in this case, it is executed for only one-third. A will becomes void if it is for a sinful purpose, or contingent upon a condition that does not occur, or if the testator apostatizes.