The Torah says about a kidnapper: "and sells him" (Exodus 21:16). The Mekhilta derives from this phrasing that the kidnapper is liable only if he sells the entire person, not half. You cannot be guilty of the capital crime of kidnapping-and-selling if you sold only a partial interest in the victim.
The passage then analyzes additional phrases. "And he is found" — the Mekhilta explains that "finding" in legal contexts always requires witnesses. The kidnapper must be discovered through witness testimony, not merely through the victim's own report.
"In his hand" — this phrase, the Mekhilta teaches, always means "in his domain" or "under his control." The kidnapped person must be found under the kidnapper's authority. Even though there is no direct proof for this interpretation, the Mekhilta finds supporting examples elsewhere in Scripture. (Numbers 21:26) says: "And he took all his land from his hand" — meaning from his domain, not literally from his physical hand. (Genesis 24:10) says: "And the servant took ten camels and all the good of his master in his hand" — meaning under his control, since a person cannot literally hold ten camels in his hands.
This analysis demonstrates how the Mekhilta built legal definitions word by word. Each phrase in the kidnapping verse yields a separate legal requirement. The crime is complete only when all elements align: full sale, verified by witnesses, while the victim was in the kidnapper's domain.