שָׁל֥וֹשׁ עָרִ֖ים תַּבְדִּ֣יל לָ֑ךְ בְּת֣וֹךְ אַרְצְךָ֔ אֲשֶׁר֙ יְהוָ֣ה אֱלֹהֶ֔יךָ נֹתֵ֥ן לְךָ֖ לְרִשְׁתָּֽהּ׃
Te apartarás tres ciudades en medio de tu tierra que SEÑOR tu Dios te da para que la poseas.
Sifrei Devarim
(Devarim 19:2) "Three cities": of average size, not very small and not very large. "shall you set aside for yourself": and not for others (i.e., gentiles).