מלכים ב, פרק י״ט, פסוק ט׳

A sudden military threat forces the Assyrian army to alter its strategy and divert its forces away from Judah. The King of Assyria receives word concerning Tirhakah, the King of Cush, who is ruling over Egypt at the time, and prepares to meet him in battle [מצודת דוד, ביאור שטיינזלץ]. Because a powerful empire backs the Cushite king, the Assyrian monarch decides to redirect his troops from the minor campaign in Judah to face the major war in Egypt [ביאור שטיינזלץ].

However, before departing, Rabshakeh dispatches messengers to King Hezekiah once again, this time utilizing official written letters [ביאור שטיינזלץ]. The primary approach among commentators is that this additional mission was designed to deliver a clear and threatening message. The King of Assyria wants Hezekiah to know that he is not fully retreating or returning to his homeland. Instead, he is merely leaving temporarily to fight the Cushites, with every intention of coming back afterward to finish his campaign in Judah.