A moment of intense public humiliation becomes a profound display of spiritual surrender. When faced with vicious insults from a political enemy, King David chooses not to retaliate, revealing a vast gap between his own worldview and the militaristic mindset of his commanders. He rejects their desire for vengeance, highlighting a deep ideological distance between them. He cannot understand the enmity that drives them to demand violence against his explicit wishes [מצודת דוד, ביאור שטיינזלץ], and instead, he simply allows the man to continue cursing as he pleases [רש"י, מלבי"ם].
David's acceptance stems from his belief that this humiliation is a direct decree from God. One perspective suggests that an important figure like Shimei, who served as the head of the Sanhedrin, would never dare to curse the king unless he had received a direct divine command [רש"י]. The primary approach among commentators, however, is that God did not literally speak to him. Rather, God stirred his spirit to humiliate David as a necessary punishment and atonement for the king's past sins. In this light, the curser is merely an agent of God, making any human interference pointless. Trying to stop a divine punishment would only ensure its fulfillment, much like how the brothers of Joseph inadvertently brought his dreams to life by trying to thwart them [רלב"ג, רד"ק, מצודת דוד, ביאור שטיינזלץ].
While the act of cursing may have been divinely inspired, the specific words were not entirely mandated. God decreed the humiliation, but He did not command the man to lie. The false insults and extra abuses were added of his own free will. Nevertheless, David accepts the abuse with love. By choosing restraint when he easily had the power to order an execution, David hopes that God will see his sorrow and tears, turning his quiet endurance into a merit that atones for his wrongdoings [חומת אנך].
Furthermore, the insults themselves hold no real power to harm David. If the man is acting entirely on his own, the public already knows that the accusations are completely false—David never murdered his political rivals or stole the throne—so there is no genuine shame. On the other hand, if the man is truly acting as God's messenger, then no human being has the right to question his actions or demand an explanation [מלבי"ם].