A king receives a devastating prophecy about the future destruction of his kingdom and the exile of his descendants. Yet, his response appears unusually calm, perhaps even self-centered. It is deeply puzzling how a righteous leader could seemingly ignore the tragic fate awaiting his children and refer to such a harsh decree as a good thing.
The primary approach among commentators is that Hezekiah simply accepts the divine judgment. He submits to God's decree and immediately explains that he draws comfort from the guarantee of personal peace. Because the prophet's message implies that the disaster will only strike during the time of his grandchildren, the king does not fear what will happen after his death [רש״י, מצודת דוד, ביאור שטיינזלץ].
A more nuanced perspective suggests the king divided his reaction into two distinct thoughts [מלבי״ם, שד״ל]. First, he confesses his wrongdoing. He recognizes his own foolishness in proudly displaying his wealth, fully accepting the prophet's rebuke and the justice of God. Second, he addresses the future. Hezekiah understood that the punishment destined for later generations was not solely a result of his own mistake, but would be triggered by the future sins of the people. Therefore, there was no reason to pray for the decree to be canceled immediately [שד״ל]. Additionally, he relied on an established rule of prophecy: a negative decree regarding his descendants could still be reversed if they improved their behavior. However, the positive implication of God's message—that disaster would not strike during his own lifetime—was absolute and unchangeable. He therefore rejoices in the guaranteed peace of his own life while leaving room for hope that his children might change their future [מלבי״ם].
Taking a completely different view, another interpretation suggests that Hezekiah was actually consumed by deep sadness. In this light, his positive reaction does not refer to the prophecy of destruction he just heard, but rather to God's earlier promise to heal him and add fifteen years to his life. Upon hearing of the impending doom, Hezekiah regretted asking for more time, terrified that he might live to witness the disaster with his own eyes, feeling that death would be better than living in disgrace. His response is therefore a condition: the extension of his life is only a good thing provided there is peace and truth during his days. He prays that the Babylonian king will remain at peace with him and that the tragedy will not unfold while he is still alive [אברבנאל].
On a conceptual level, the king's reaction reflects a grasp of the foundational pillars that sustain the world: justice, truth, and peace. Since the divine attribute of justice is what demanded the future destruction, Hezekiah finds comfort in securing the two remaining pillars. He expresses gratitude that, at the very least, truth and peace will accompany him throughout the rest of his life [חומת אנך].