דברי הימים ב, פרק ט״ז, פסוק ח׳

A sharp rebuke is directed at the king for his sudden failure to trust God, using the memory of a past miraculous victory to highlight his current lack of faith. The criticism raises a simple question about why the king became so afraid now. If his panic stemmed from facing an alliance of two kings, he is reminded that he previously stood against a massive coalition of two great nations during the war of Zerah the Cushite [מלבי ם]. The Lubim nation had indeed joined the Cushites in that earlier battle, even though they were left out of previous historical accounts of the event [מצודת דוד]. That past invasion, driven by the Egyptian army and its allies, posed an overwhelming and incredibly difficult threat [ביאור שטיינזלץ].

Alternatively, if the king's current fear was driven by the sheer size of the enemy forces, he is reminded of the massive scale of his past enemies. Those nations had gathered an enormous military force, equipped with a vast number of chariots and horsemen [מצודת דוד, מלבי ם]. Despite facing such impossible odds back then, the king chose to rely completely on God. Because of that unwavering trust, God delivered the massive army into his hands, allowing him to secure a complete victory and drive the threat away [מלבי ם, ביאור שטיינזלץ].