Albert Barnes Commentary Isaiah 38:20

"Jehovah is [ready] to save me: Therefore we will sing my songs with stringed instruments All the days of our life in the house of Jehovah." — Isaiah 38:20 (ASV)

The Lord was ready to save me — He was prompt, quick to save me. He did not hesitate or delay.

Therefore we will sing my songs — That is, my family and nation. The song of Hezekiah was evidently designed not as a mere record, but to be used in celebrating the praises of God, and probably in a public manner in the temple. The restoration of the monarch was a fitting occasion for public rejoicing, and it is probable that this ode was composed to be used by the company of singers who were employed constantly in the temple.

To the stringed instruments — We will set it to music and will use it publicly (see the notes at Isaiah 5:12).