Deut 17:14-17

Limitations of Royal Authority 14When you have come into the land that the Lord your God is giving you, and have taken possession of it and settled in it, and you say, “I will set a king over me, like all the nations that are around me,”15you may indeed set over you a king whom the Lord your God will choose. One of your own community you may set as king over you; you are not permitted to put a foreigner over you, who is not of your own community.16Even so, he must not acquire many horses for himself, or return the people to Egypt in order to acquire more horses, since the Lord has said to you, “You must never return that way again.”17And he must not acquire many wives for himself, or else his heart will turn away; also silver and gold he must not acquire in great quantity for himself.