Deuteronomy 17:14-15

14When thou art come unto the land which the Lord thy God giveth thee, and shalt possess it, and shalt dwell therein, and shalt say, I will set a king over me, like as all the nations that are about me; 15Thou shalt in any wise set him king over thee, whom the Lord thy God shall choose: one from among thy brethren shalt thou set king over thee: thou mayest not set a stranger over thee, which is not thy brother.