John Gill Commentary 2 Chronicles 30:20

"And Jehovah hearkened to Hezekiah, and healed the people." — 2 Chronicles 30:20 (ASV)

And the Lord hearkened to Hezekiah
Heard his prayer, and accepted of it, and granted what he desired:

and healed his people ;
that is, forgave their sins, as Kimchi interprets it; forgiveness being expressed by healing, for which he refers to (Psalms 41:4) to which may be added (Psalms 103:3) (Malachi 4:2) and which was known either by a prophet sent to declare it, or by not punishing them for their offence.