The Mekhilta DeRabbi Yishmael addresses a legal question about the identity of a wife given to a Hebrew servant by his master. The Torah states that if a master gives his servant "a wife," and she bears children, "the woman and her children shall belong to her master" when the servant goes free (Exodus 21:4). But who is this woman?
The Mekhilta states plainly: Scripture here speaks of a Canaanite woman. A master may give his Hebrew servant a Canaanite maidservant as a wife during his years of service. This is the only scenario that fits the Torah's language.
But the Mekhilta anticipates an objection. Perhaps the Torah is speaking of a Hebrew woman? Perhaps the master gives the servant an Israelite wife? The text rejects this possibility based on the end of the verse: "the woman and her children shall belong to her master." A Hebrew woman cannot "belong" to a master in this way. An Israelite woman is not property. She cannot be retained by the master when her husband goes free.
The fact that the woman and her children remain with the master after the servant's departure proves she must be a Canaanite maidservant, whose legal status differs. The verse's own language — the concept of belonging to the master — eliminates any possibility that an Israelite woman is meant.
This passage demonstrates the Mekhilta's characteristic method of close reading: raising the strongest possible objection, then resolving it by letting the Torah's own words provide the answer. The legal status embedded in a single phrase determines the identity of an unnamed person in the narrative.