The Mekhilta asks a question about Kazbi (also known as Cozbi), the Midianite woman who played a central role in the sin at Baal Peor. The verse calls her "the daughter of a prince of Midian, their sister" (Numbers 25:18). But the rabbis immediately object: was she really the "sister" of all Midian?
Her father Tzur was "the head of the peoples of a father's house in Midian" (Numbers 25:15) — a tribal chief, not a brother to every Midianite. So why does the Torah call Kazbi "their sister," as though she were a blood relative of the entire nation?
The Mekhilta's answer is stunning: because she risked her life for her people. Kazbi's act — seducing Israelite men to draw them into idolatry — was not done for personal gain or pleasure. She deliberately put herself in mortal danger to protect Midianite interests. She walked into the Israelite camp knowing she might not walk out alive. And for that act of self-sacrifice on behalf of her nation, all of Midian was called by her name. She became their "sister" — their representative, their embodiment.
The rabbis are not praising Kazbi's morality. They are recognizing a principle: when someone risks everything for their people, that people becomes identified with them. The title "sister" is earned through sacrifice, not blood. Even an enemy's courage is acknowledged in the Mekhilta's unflinching analysis.