Deuteronomy 17:16-20

16Only he must not acquire many horses for himself or cause the people to return to Egypt in order to acquire many horses, since the Lord has said to you, 'You shall never return that way again.'

17And he shall not acquire many wives for himself, lest his heart turn away, nor shall he acquire for himself excessive silver and gold.

18"And when he sits on the throne of his kingdom, he shall write for himself in a book a copy of this law, approved by the Levitical priests.

19And it shall be with him, and he shall read in it all the days of his life, that he may learn to fear the Lord his God by keeping all the words of this law and these statutes, and doing them,

20that his heart may not be lifted up above his brothers, and that he may not turn aside from the commandment, either to the right hand or to the left, so that he may continue long in his kingdom, he and his children, in Israel.