Charles Ellicott Commentary 2 Chronicles 6:39

"then hear thou from heaven, even from thy dwelling-place, their prayer and their supplications, and maintain their cause, and forgive thy people who have sinned against thee." — 2 Chronicles 6:39 (ASV)

Their supplications. —In Kings, the term is singular; and so it is in some manuscripts, the Septuagint, Syriac, and Arabic. The plural is found nowhere else and is probably incorrect here.

And forgive thy people. —This is the first clause of 1 Kings 8:50; and from this point to the end of Solomon’s Prayer, the two texts are wholly dissimilar.