This miraculous help to the besieged Jerusalem occurred at the same time as another, not less miraculous event. Three days before Sennaherib‘s army had been smitten at the gates of Jerusalem, Hezekiah fell seriously ill, and the prophet Isaiah came to tell him that he was to die. The prophet also told him that G‑d was greatly displeased because Hezekiah had not married. Now Hezekiah who had the gift of prophetic vision knew that his children would mislead the Jewish people. Therefore he had refused to marry. But Isaiah told him that human beings must not interfere with G‑d‘s ways of governing the world. All man can do is to live according to G‑d’s commands, and fulfill his duties. Everything else is in G‑d’s hands.
When the king heard the prophet’s words, “Set thy house in order for thou shalt die,” he turned his face towards the wall and fervently implored G‑d that he might live. His prayer was accepted, and G‑d sent Isaiah back to tell him that he would recover and that his life would be prolonged for fifteen years. When Hezekiah asked for a sign that he was to get well again, Isaiah replied that the shadow on the sun-dial would recede ten degrees. Indeed this miracle occurred. Isaiah put a fig-plaster on Hezekiah’s boils, and the king recovered completely.
This last miracle proved to the entire world that Hezekiah was a favorite of G‑d. The day of Hezekiah’s recovery was the first day of Passover. While the people gathered in the Holy Temple to praise G‑d, the good news of the Divine punishment that had overtaken Sennaherib’s army reached the crowded city and greatly intensified the joy and happiness of the people.
Read about the Jewish Historical account of King Hezekiah at Chabod