שופטים ושטרים תתן לך. (סנהדרין טז) מנין שממנים ב"ד לכל ישראל? ת"ל שופטים תתן לך. ומנין שממנים שוטרים לכל ישראל? ת"ל שוטרים תתן לך.
(Devarim 16:18) "Judges and officers shall you appoint for yourself": Whence is it derived that a beth-din is appointed for all of Israel? From "Judges … shall you appoint for yourself." And whence is it derived that (police) officers are appointed for all of Israel? From "… officers shall you appoint for yourself."