Deuteronomy 17:14-15

14When thou art come into the land which the LORD thy God giveth thee, and shalt possess it, and shalt dwell in it, and shalt say, I will set a king over me, like as all the nations that are about me; 15Thou shalt surely 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, who is not thy brother.