As explained in the previous article, monarchy has as many risks as benefits. It is only desirable for the Jewish people to have a king if he acts as a representative of Hashem and no more. The Torah commands a series of Mitzvos that give the king the power to lead the nation while remembering that he is no more than a representative of the true King of the Jewish people.

The king must be Jewish. This is because Jews are compassionate by nature (Chinuch), and people are especially compassionate toward their brethren. With this Mitzvah, the Torah ensures that the king will not act selfishly and cruelly toward the Jewish people. Secondly, if the king is an idolater, he will lead the Jewish people toward idolatry (Rashbam). It is further possible that this Mitzvah ensures that the king’s control over the people will be stable and efficient, for the Jewish people will only be willing to extend their loyalty to a fellow Jew whom they can view as their faithful representative.

We also find elsewhere that the Torah requires us to grant the king supreme power to enable him to control the nation. We are commanded not to curse a king (Shemos 22:27), and Sefer Hachinuch explains that speaking ill about the king lessens his respect and authority, and therefore his ability to lead.

The king may not have excessive horses. The Torah explains that this is a safeguard against returning to Egypt, where superior Arabian horses are bred. In addition, Abarbanel suggests that the Torah means to discourage the king from having too many horses because, in the olden times, military strength depended to a great extent on the number of horses. Since a Jewish king is meant to be no more than a representative of Hashem, and his military victories are linked to his loyalty to Hashem, the Torah forbids him from overinvesting in his armies lest he forget his dependency upon Hashem. A king who relies on his own strength might feel a need to turn to his Egyptian neighbors for support in times of war, so the verse proceeds to warn against going there.

The idea that returning to Egypt implies a lessening of dependency on Hashem is found elsewhere in the Torah as well. In Parashas Eikev, the Torah contrasts Eretz Yisrael and Egypt, pointing out that Eretz Yisrael is dependent on Hashem’s willingness to grant rain, while Egypt has a constant stream of water from the Nile (see Devarim 11:10-12). The inhabitants of Eretz Yisrael are thus compelled to obey Hashem lest they die of drought, and “His eyes are constantly upon Eretz Yisrael,” judging its merit and seeing to its needs — while the inhabitants of Egypt receive little Divine attention. By forbidding us to return to Egypt, Hashem compels us to be dependent upon Him.

The king may not have excessive wives. A king would commonly marry multiple wives in order to increase his power, for two reasons: Firstly, he could marry the daughters of other kings and thereby forge solid, familial alliances. Secondly, his sons would be most loyal to him as officers. However, the Torah forbids a king from having excessive wives, which the Sages determined to be eighteen, lest they influence his heart.

A wife tends to influence her husband according to her wishes, and this means that the more wives a king has, the less he can be focused on the welfare of the people under his charge (Sefer HaChinuch). The risk of this occurring increases when many rival wives compete for a greater share of his attention. Another reason is that excessive pleasure dulls the king’s mind, saps his strength, and lessens his ability to rule (Abarbanel).

The king may not hoard money. The Torah places this prohibition alongside the prohibition against taking excessive wives, which suggests that they share the same general reason: they influence a person's heart. Abundant wealth makes a person haughty, which makes a king forget his total reliance upon Hashem.

The king must have a miniature Sefer Torah that accompanies him at all times, as well a normal-sized Sefer Torah in his treasury. In order to control the people according to Hashem’s will, it is imperative that the king knows Hashem's will and is constantly focused upon it, and this requires constant Torah study. Even when he does not actually read the Torah, its presence is a visible reminder of the invisible God Who is watching the king's every move. The king has no authority above him, so he more than anyone needs to remember Hashem's authority (Sefer HaChinuch).

The passage of the king's Mitzvos ends with a blessing: so that he and his descendants reign for lengthy days (14:20). This is a hidden word of caution, that if he does not abide by the above laws, he will not merit a lengthy reign. Chizkuni sees in this verse a source for the customary proclamation by a coronation ceremony: "Long live the king!"

In summary, a king must be careful not to let his riches and power cause him to become haughty and forget the true source of power, by exercising measures of restraint and constantly remembering the Torah and its contents. The Sages indicate that that this applies to every Jew, only to a smaller degree (Shaarei Teshuvah 3:24). The more Hashem grants us, the more it is incumbent upon us to remind ourselves from Whom it all comes, and what He expects us to do with it.