2 Chronicles 20:21 Commentary - English Annotations on the Holy Bible by Matthew Poole
With the people, i.e. with the elders or chief of the people; partly to take their advice about the expediency of the thing; and partly that they might excite and prepare themselves, and the people under them, to this great work of praising God.
He appointed singers unto the Lord; to the honour and service of God.
The beauty of holiness, or, the glory, or magnificence, or majesty of holiness, i.e. (by a vulgar Hebraism,) the Holy Majesty; a periphrasis of God. Or, according to the beauty or magnificence of the sanctuary, i.e. in the same comely order and magnificent manner as they used to do it in the temple; where the following song was usually sung, as 2Ch 5:13; 7:3,6.
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English Annotations on the Holy Bible by Matthew Poole
Matthew Poole (1624–1679) wrote English Annotations on the Holy Bible, completing the chapters as far as Isaiah 58 before his death in 1679. The rest of the Annotations were completed by friends and colleagues among his Nonconformist brethren. The first printing of the completed edition was in 1685, 2 volumes folio, followed by editions in 1688, 1696 (with valuable chapter outlines added by the editors, Samuel Clark and Edward Veale), and the 4th and definitive edition in 1700, the basis of all others.