This is a writing by Hezekiah king of Judah after his illness and recovery:
9. The writing of Hezekiah. Though sacred history gives no account of this writing, yet it deserves to be recorded, and is highly worthy of observation; for we see that Hezekiah was unwilling to pass in silence, or to bury in forgetfulness, so remarkable a blessing which he had received from God.
We have here Hezekiah's thanksgiving-song, which he penned, by divine direction, after his recovery. He might have taken some of the psalms of his father David, and made use of them for his purpose; he might have found many very pertinent ones. He appointed the Levites to praise the Lord with the words of David, Ch2 29:30.
Commenting on Isaiah 38:9-22
I said, in the cutting off of my days,.... When he was told that he should die, and he believed he should; this he calls a "cutting off" in allusion to the weaver's web, Isa 38:12 and a cutting off "his days", he being now in the prime of his age, about thirty nine or forty years of age, and not arrived to the common...