4 Then the word of Yahweh came to Isaiah, saying, 5 “Go, and tell Hezekiah, ‘Thus says Yahweh, the God of David your father, “I have heard your prayer. I have seen your tears. Behold, I will add fifteen years to your life. 6 I will deliver you and this city out of the hand of the king of Assyria, and I will defend this city.
Matthew Henry's Commentary on Isaiah 38:4-6
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.