Deuteronomy 17:16-18

American Standard Version

¹⁶ Only he shall not multiply horses to himself, nor cause the people to return to Egypt, to the end that he may multiply horses; forasmuch as Jehovah hath said unto you, Ye shall henceforth return no more that way. ¹⁷ Neither shall he multiply wives to himself, that his heart turn not away: neither shall he greatly multiply to himself silver and gold.

¹⁸ And it shall be, when he sitteth upon the throne of his kingdom, that he shall write him a copy of this law in a book, out of that which is before the priests the Levites: