5 "Go and speak with Hezekiah. Give him this Message from me, God, the God of your ancestor David: 'I've heard your prayer. I have seen your tears. Here's what I'll do: I'll add fifteen years to your life. 6 And I'll save both you and this city from the king of Assyria. I have my hand on this city. 7 "'And this is your confirming sign, confirming that I, God, will do exactly what I have promised. 8 Watch for this: As the sun goes down and the shadow lengthens on the sundial of Ahaz, I'm going to reverse the shadow ten notches on the dial.'" And that's what happened: The declining sun's shadow reversed ten notches on the dial.
Matthew Henry's Commentary on Isaiah 38:5-8
Commentary on Isaiah 38:1-8
(Read Isaiah 38:1-8)
When we pray in our sickness, though God send not to us such an answer as he here sent to Hezekiah, yet, if by his Spirit he bids us be of good cheer, assures us that our sins are forgiven, and that, whether we live or die, we shall be his, we do not pray in vain. See 2 Kings 20:1-11.