Isaiah - Chapter 38
Chizkiyahu's Illness, Recovery and Psalm
This chapter parallels II Kings chapter 20.
King Chizkiyahu became ill and Isaiah went to visit him. Isaiah told Chizkiyahu to get his affairs in order, because he was going to die. Chizkiyahu turned to the wall and prayed and cried. G-d told Isaiah to return to the king and let him know that his prayers were answered; G-d has granted him another 15 years. Furthermore, He would save the city from the onslaught of the Assyrian army. (This incident occurred before the plague wiped out the Assyrian army, as described in the previous chapter.) As a sign, the shadow cast by the sun went back ten steps. (Compare the description of this event with that in Kings.)
After his recovery, Chizkiyahu wrote a psalm of thanks. In it, he said that he had despaired that he was going to die, missing out on the rest of his years. No longer would he be able to serve G-d on Earth, as he would be in the Next World, separated from his people. The more he strengthened himself, the weaker he would become. Chizkiyahu moaned in his illness like the sound of a bird, praying to G-d to "steal" him from the hand of death - and He did! So how can Chizkiyahu ever repay G-d for the gift of extra years? G-d will ultimately resurrect the dead and he renewed Chizkiyahu's life in advance of that. Even tidings of peace were bitter, for he expected to die, but it pleased G-d to let Chizkiyahu live, despite his sins. The dead are not able to thank G-d; that's the domain of the living, like Chizkiyahu today. ("Today" meaning when he wrote his psalm, not when you're reading it.) As thanks to G-d, Chizkiyahu's psalms would be sung in the Temple for the rest of his life.
Isaiah took a cake of figs and pressed it on Chizkiyahu's boil, healing it. From this, Chizkiyahu knew he would be healed and would be able to continue to serve G-d.