Albert Barnes Commentary Isaiah 38:9

"The writing of Hezekiah king of Judah, when he had been sick, and was recovered of his sickness." — Isaiah 38:9 (ASV)

The writing of Hezekiah - This is the title of the following hymn, a record that Hezekiah made to celebrate the goodness of God in restoring him to health. The writing itself is poetry, as indicated by the parallelism and by the general structure.

It is in many respects quite obscure—an obscurity perhaps arising from the brevity and conciseness apparent in the whole piece. It is remarkable that this song or hymn is not found in the parallel passage in the Book of Kings. The reason it was omitted there and inserted here is unknown. It is possible that it was drawn up for Hezekiah by Isaiah and inserted here as a part of his composition, though adopted by Hezekiah and declared to be his—that is, expressing the gratitude of his heart on his recovery from his disease.

It was common to compose an ode or hymn of praise on the occasion of deliverance from calamity or any remarkable interposition of God (see the notes at Isaiah 12:1; Isaiah 25:1; Isaiah 26:1). Many of the Psalms of David were composed on such occasions and were expressive of gratitude to God for deliverance from impending calamity. The hymn or song is composed of two parts. In the first part (Isaiah 38:10–14), Hezekiah describes his feelings and his fears when he was suffering, and especially his apprehension at the prospect of death; and the second part (Isaiah 38:15–20) expresses praise to God for his goodness.