The Mekhilta DeRabbi Yishmael identifies a critical distinction in the commandment "You shall not steal." The eighth of the Ten Commandments is not about stealing property. It is about stealing people.
The reasoning begins with (Exodus 21:14), which states: "One who steals a man and sells him" shall be put to death. That verse establishes the punishment for kidnapping. But a punishment requires a corresponding prohibition. Where is the explicit commandment that forbids the act? The answer is "You shall not steal" in the Ten Commandments. This is the exhortation against stealing a soul, meaning the kidnapping of a human being.
An obvious objection arises: perhaps "You shall not steal" in the Ten Commandments refers to stealing money or property, the ordinary meaning of theft. The Mekhilta addresses this directly. (Leviticus 19:11) separately states "You shall not steal," and that verse is the prohibition against stealing money and possessions. Since the Torah already has a dedicated commandment for property theft elsewhere, the version in the Ten Commandments must be addressing something different.
The conclusion is stark: "You shall not steal" in the Decalogue means "You shall not steal a soul." Kidnapping, the theft of a human being, stands alongside murder and adultery in the Ten Commandments. Property theft, while certainly forbidden, is addressed in a different section of the Torah.
This reading elevates the commandment dramatically. The Ten Commandments do not waste space on ordinary theft. They reserve their prohibition for the most extreme violation of human dignity: treating a person as an object to be taken and sold.