Deuteronomy 17:15

17:15 you must select without fail a king whom the Lord your God chooses. From among your fellow citizens you must appoint a king – you may not designate a foreigner who is not one of your fellow Israelites.

Deuteronomy 17:20

17:20 Then he will not exalt himself above his fellow citizens or turn from the commandments to the right or left, and he and his descendants will enjoy many years ruling over his kingdom in Israel.