Deuteronomy 17:16-20

161In any case, he is not to acquire many horses for himself, nor shall he 2make the people return to Egypt in order to acquire many horses, since 3the Lord has said to you, ‘You shall never again return that way.’ 17And 4he shall not acquire many wives for himself, so that his heart does not 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, that he shall write for himself a copy of this Law on a scroll 56in the presence of the Levitical priests. 19And it shall be with him, and he shall read it 7all the days of his life, so that he will learn to fear the Lord his God, 8by carefully following all the words of this Law and these statutes, 20so that his heart will not be haughty toward his countrymen, 9and that he will not turn away from the commandment to the right or the left, so that he and his sons may 10live long in his kingdom in the midst of Israel.