דברים, פרק י״ז, פסוק כ׳

The ultimate moral and spiritual vision for a monarch is not absolute power, but a character shaped by divine limits. The restrictions placed on accumulating horses, wives, and wealth, alongside the duty to carry a Torah scroll, are designed to mold the king's personality and align his rule with the will of God [ביאור שטיינזלץ]. The primary approach among commentators is that the central purpose behind these prohibitions is to guard the king against pride, lust, and greed [רוב הפרשנים, אדרת אליהו]. Constant engagement with the Torah serves as a vital shield against arrogance [אור החיים, העמק דבר]. The monarch is required to cultivate a profound humility, ensuring he does not feel superior even to the simplest members of the nation [הכתב והקבלה, ביאור יש"ר]. From this, a logical conclusion is drawn: if a king, holding the highest earthly office, is forbidden from being haughty, an ordinary person must certainly avoid pride, a trait deeply hated by God [רמב"ן, הטור הארוך, רלב"ג].

However, this required humility has specific boundaries. While the king must remain humble toward his fellow Israelites, he is permitted to project pride and strength toward enemy nations [אדרת אליהו]. Furthermore, his relationship with his brethren dictates how he manages his wealth; he may collect taxes legally from the people, but he is strictly forbidden from taking consecrated property for personal use [פני דוד, צפנת פענח].

The mandate to never turn away from the commandment is the underlying reason the king must carry his Torah scroll everywhere [רא"ש, חזקוני]. Because earlier instructions already established the duty to observe the entire Torah, the primary approach among commentators is that this specific injunction refers to absolute obedience to a prophet [רש"י, מזרחי, גור אריה]. Even though the king holds supreme political authority, he must recognize that God's word, delivered through a prophet, supersedes his own power [העמק דבר]. He is obligated to obey a prophet even in minor matters, or when given a temporary directive that appears to contradict standard Torah law, as if being told that right is left [פני דוד, אדרת אליהו]. Interestingly, while humility is demanded in his personal demeanor toward the nation, when a prophet commands him to battle wickedness and execute justice, the king must act with boldness, fearlessness, and might [הכתב והקבלה, ביאור יש"ר].

The promise of a prolonged reign is entirely conditional on maintaining these moral and spiritual standards [מלבי"ם]. Commentators note that this positive guarantee carries a severe warning: a king who deviates from a prophet's instruction, even a minor one, will be punished and lose his crown. The classic example is King Saul, who lost his kingdom because he failed to wait for the prophet Samuel as instructed [רש"י, מזרחי, רבנו בחיי]. A specific blessing for a long life is particularly necessary for a ruler, as the heavy burdens of power and authority naturally tend to shorten a person's lifespan [חזקוני].

Finally, the promise extends to the king's descendants, establishing the principle of a hereditary monarchy. One might think that if a king lives an unusually long life, his sons might lose their opportunity to rule; therefore, God assures that they too will inherit the throne [אלשיך]. A son takes absolute precedence over any other candidate provided he is worthy, particularly in his fear of God, even if he does not quite match his father's level of wisdom [רש"י, מזרחי]. Because the crown passes by inheritance, a royal heir does not require the traditional anointing with oil unless there is a public dispute over the succession, as occurred with King Solomon [רבנו בחיי, תורה תמימה]. This concept of hereditary succession is not limited to the monarchy but applies to all positions of leadership and authority among the Israelites [תורה תמימה, ברכת אשר על התורה].