From their uncleanness; which itself was a spiritual disease, and which probably produced a disease, or distemper, or trouble in their minds and consciences; which also had formerly brought, and might justly now bring, even outward diseases upon the body, or, at least, guilt, which is a disease upon the soul; from all which the Lord was pleased now to heal them, by pardoning this their sin, and accepting them and their services, as if they had been clean; which it is likely God was pleased to manifest by some outward sign, possibly by fire from heaven consuming the sacrifices; which was the usual token of God's approbation, as hath been formerly noted more than once.
Related Commentaries of 2 Chronicles 30:20
2 Chronicles 30:20
20 And the LORD hearkened to Hezekiah, and healed the people.