Deuteronomy 17:18-20

And when he has taken his place on the seat of his kingdom, he is to make in a book a copy of this law, from that which the priests, the Levites, have in their care: And it is to be with him for his reading all the days of his life, so that he may be trained in the fear of the Lord his God to keep and do all the words of this teaching and these laws: So that his heart may not be lifted up over his countrymen, and he may not be turned away from the orders, to one side or the other: but that his life and the lives of his children may be long in his kingdom in Israel.