Deuteronomy 17:14-17

When thou art come unto the land which Jehovah thy God giveth thee, and shalt possess it, and shalt dwell therein, and shalt say, I will set a king over me, like all the nations that are round about me; thou shalt surely set him king over thee, whom Jehovah thy God shall choose: one from among thy brethren shalt thou set king over thee; thou mayest not put a foreigner over thee, who is not thy brother. 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. Neither shall he multiply wives to himself, that his heart turn not away: neither shall he greatly multiply to himself silver and gold.