Ketubot, Chapter Eleven, Mishnah Four
This mishnah deals with a widow who when selling her field either overestimates or underestimates the value of the field. The questions are, 1) is she deemed to have received her ketubah; 2) is the sale valid.
1) If a widow whose ketubah was two hundred zuz sold [land] worth a maneh for two hundred zuz or [land] worth two hundred zuz for one maneh, she has received her ketubah.
2) If her kethubah was one maneh, and she sold [land] worth a maneh and a denar for one maneh, her sale is void.
a) Even if she says, I will return the denar to the heirs, her sale is void.
b) Rabbi Shimon ben Gamaliel says: her sale is always valid unless there was so much land there as to allow her to leave a field of nine kab, and from a garden an area of half a kab, or, according to Rabbi Akiba, a quarter of a kab.
3) If her ketubah was four hundred zuz and she sold [land] to [three] persons, to each for one maneh, and to a fourth [she sold] what was worth a maneh and a denar for one maneh, [the sale] to the last person is void but [the sale] to all the others are valid.
Section one: There are two cases mentioned in this section. In both the widow is selling her husbands land in order to collect her ketubah, which is worth 200 denar. In the first case she sells a field that was worth 100 zuz (a maneh) for 200 denar. Although her husbands estate only lost land worth 100 zuz, since she received 200 denar, she has received her ketubah and does not receive anymore. In the second case, she sells land worth 200 zuz for 100 zuz. Since her husbands estate sold off a field worth 200 zuz, it has paid off her ketubah, even though she only received 100. In other words, the husbands estate always gets the benefit of the doubt.
Section two: If she sells land worth more than her ketubah, the sale is invalid. This land is not hers and she only had permission to sell up to the value of her ketubah. Even if she says that she will pay back the extra denar to her husbands inheritors, she is not allowed to do, if the inheritors want back their land.
Rabbi Shimon disagrees and says that the sale is only nullified if the extra amount sold would have left the inheritors with a field in which nine kab of seed can be planted, about 3750 square amot (a little over 60 x 60 amot). If it was a garden of vegetables, the size is smaller, about 208 square amot or 104 square amot according to Rabbi Akiba. If the size of the extra land sold is smaller than this, the sale is valid.
Section three: If her ketubah was 400 zuz, and she sold fields worth 100 to three different people and to the last person she sold a field worth 101, only the last sale is invalid. Each sale is considered on its own merits, and it was only the last sale which went over the limit.