Charles Ellicott Commentary 2 Chronicles 20:19

"And the Levites, of the children of the Kohathites and of the children of the Korahites, stood up to praise Jehovah, the God of Israel, with an exceeding loud voice." — 2 Chronicles 20:19 (ASV)

And the Levites. — The Levites are the first to rise up to break forth into a hymn of thanksgiving.

Of the children of the Kohathites, and of the children of the Korhites. — Sons of the Kohathites specifies the clan, and sons of the Korhites the house of the musicians who rose up on this occasion. The Korhites were the leading division of Kohath (1 Chronicles 6:22). And is explanatory; that is, namely, some of the sons of Korah. The sons of Korah were a guild of Levitical musicians of the first rank. (Compare the headings of many psalms, e.g.,Psalms 44–49, connecting them with their authorship.)

To praise the Lord God of Israel. — 1 Chronicles 16:14 (hallel).