- Avadim – non-Jewish slaves
- Shetarot – notes or contracts
- Karka’ot – real estate
- Hekdeshot – things that have been consecrated to the Temple.
The first rule of the Mishna is that the rules of ona’ah (exploitation) – rules that forbid overcharging or undercharging at the time of sale – do not apply in any of these cases. The Gemara explains that this is learned from the passage that is the source of the prohibition of ona’ah (Vayikra 25:14), where the Torah teaches that ona’ah is forbidden when something is sold or bought me-yad amitekhah – from your fellow’s hand. This is understood to exclude real estate which does not transfer from hand to hand. The other cases are derived by the Gemara from the law about real estate.
Although the source for this law is biblical, some suggest logical reasons that may be the foundation for these ideas. One idea is that real estate cannot be valued the same way movable property can, and has greater importance than other things, since it lasts forever.
Another set of laws that does not apply to these cases are the penalties that a thief must pay if the object is stolen over and above returning the value of the stolen object – usually kefel (double payment), and occasionally four or five times the object’s worth, if it was an ox or a sheep that was stolen and then killed or sold. A question that is raised by the rishonim is how these rules can apply to real estate – how can immovable property be stolen? Tosafot in Massekhet Bava Kamma offers two suggestions – either we are talking about a case of masig gevul – someone who tampers with the border markings between fields, or we are talking about a case of something that is mehubar la-karka – something that is connected to the ground, and therefore has the same rules as the land itself.