2 Kings 20:11
And Isaiah the prophet cried unto the LORD: and he brought the shadow ten degrees backward, by which it had gone down in the dial of Ahaz. And Isaiah the prophet cried unto the LORD: and he brought the shadow ten degrees backward, by which it had gone down in the dial of Ahaz.
In answer to Isaiah's cry to the Lord, God himself miraculously brought the shadow backward ten degrees by which it had gone down on the dial of Ahaz. That backward movement was an extraordinary sign to Hezekiah that God had heard his prayer and would keep His promise to heal him. It granted him a new lease of life, adding fifteen years to his life. His healing joined divine miracle with practical means, for a fig was laid on the affected part, showing that using remedies and working in harmony with natural law does not deny faith.
The wonder was noticed by Babylonian astronomers and astonished them. It prompted the king of Babylon to send ambassadors to Hezekiah to learn about the God who had performed it. The recovery and its sign form the setting for a warning about Hezekiah's later failure, when the visit of those Babylonian ambassadors became a test that revealed what was in his heart.