Deuteronomy 17:14-20

When you have come into the land which the LORD, your God, is giving you, and have taken possession of it and settled in it, should you then decide, “I will set a king over me, like all the surrounding nations,” you may indeed set over you a king whom the LORD, your God, will choose. Someone from among your own kindred you may set over you as king; you may not set over you a foreigner, who is no kin of yours. But he shall not have a great number of horses; nor shall he make his people go back again to Egypt to acquire many horses, for the LORD said to you, Do not go back that way again. Neither shall he have a great number of wives, lest his heart turn away, nor shall he accumulate a vast amount of silver and gold. When he is sitting upon his royal throne, he shall write a copy of this law upon a scroll from the one that is in the custody of the levitical priests. It shall remain with him and he shall read it as long as he lives, so that he may learn to fear the LORD, his God, and to observe carefully all the words of this law and these statutes, so that he does not exalt himself over his kindred or turn aside from this commandment to the right or to the left, and so that he and his descendants may reign long in Israel.