2 Chronicles 32:24
In those days Hezekiah was sick to the death, and prayed unto the LORD: and he spake unto him, and he gave him a sign. In those days Hezekiah was sick to the death, and prayed unto the LORD: and he spake unto him, and he gave him a sign.
In those days Hezekiah was sick to death, and he prayed to the LORD, and God answered him by healing him and adding fifteen years to his life. The sign God gave him was that the shadow moved backward ten degrees on the dial, confirming that God would fulfill His promise. The answer came as Hezekiah humbled himself before God and met mercy, showing that God is very near the humble and contrite to revive the spirit of the humble and the heart of the contrite, being as merciful as just and willing that none should perish but that all should come to Him for life.
His humiliation and prayers, together with the prayers of his people, preceded the Lord's overthrow of the Assyrian army by His angel when the Assyrians pressed Jerusalem. His prayer and deliverance amid danger were part of experiences meant to teach him humility and dependence on God. The healing was granted because of his persistence, not because of his goodness or because what he asked was best for him.
He pressed his petition until it was granted, making him an example of asking God to yield to one's own desire, recorded as a lasting warning that even fervent, effective prayer must be joined with complete submission to God's will. His son Manasseh was born three years after his recovery, during those added years, and Manasseh later ruled wickedly for most of his long reign. Despite what he had learned, pride afterward became the root of the great sin of his life and reign, and his later backsliding brought consequences upon the people about a hundred years afterward.
The Babylonians later noticed the sign, which gave Hezekiah an opportunity to teach them about the true God.