Baba Basra 8:5-6
Baba Basra 8:5
If a person says, “So-and-so, my firstborn son, will not receive a double portion” or “My son so-and-so will not inherit alongside his brothers,” his statement is of no consequence because he is making conditions that contradict the Torah. If a person divides his estate orally among his sons, giving more to one and less to another, or if he made the firstborn son’s share equal to those of the other sons, his words are effective; if he specifies that he is doing this as an inheritance, then his words are of no consequence. If he wrote “as a gift,” whether at the beginning, the middle or the end, then his words are effective. If someone says, “Such-and-such person will inherit me” and he has a daughter, or “My daughter will inherit me” and he has a son, his statement is of no consequence because he is making conditions that contradict the Torah. Rabbi Yochanan ben Brokah says that if he spoke of a person who is fit to inherit him, his words are effective but if he spoke of one who is not fit to inherit him, his words are ineffective. One who gives all his possessions to others and leaves out his sons, what he did is done but the Sages are displeased with such a person (for circumventing what the Torah prescribes). Rabban Shimon ben Gamliel says that if a person’s sons are unworthy, then disinheriting them is remembered to his credit.
Baba Basra 8:6
If a person says, “This is my son,” he is believed; if he says, “This is my brother,” he is not believed (to divide an estate) and the latter shares with the former in his portion. If the alleged brother dies, what he received returns to the one from whom it came. If he inherited property from someplace else, his brothers share the inheritance along with the first person. If a person dies and a document disposing with his estate is found tied to his leg, it is meaningless (because it was not delivered to the one named in the document, so the one who wrote it may have changed his mind). If he transferred possession of the document through another person, whether that person was himself one of the heirs or not, it is effective.