Jamieson, Fausset and Brown on 2 Kings 19:6

6. Isaiah said ... Be not afraid--The prophet's answer was most cheering, as it held out the prospect of a speedy deliverance from the invader. The blast, the rumor, the fall by the sword, contained a brief prediction that was soon fulfilled in all the three particulars--namely, the alarm that hastened his retreat, the destruction that overtook his army, and the violent death that suddenly ended his career.

2Ki 19:8-13. Sennacherib Sends a Blasphemous Letter to Hezekiah.