Deuteronomy 17:14-18

14“When you enter the land which the Lord your God gives you, and you 1possess it and live in it, and you say, ‘2I will set a king over me like all the nations who are around me,’ 15you shall surely set a king over you whom the Lord your God chooses, one 3from among your 4countrymen you shall set as king over yourselves; you may not put a foreigner over yourselves who is not your 5countryman. 166Moreover, he shall not multiply horses for himself, nor shall he 7cause the people to return to Egypt to multiply horses, since 8the Lord has said to you, ‘You shall never again return that way.’ 179He shall not multiply wives for himself, 10or else his heart will turn away; nor shall he greatly increase silver and gold for himself.

18“Now it shall come about when he sits on the throne of his kingdom, he shall write for himself a copy of this law on a scroll 1112in the presence of the Levitical priests.