Are there not with you ... sins against the Lord? - The ten tribes had fallen away from the true faith far more completely and more hopelessly than the two. It was not for them to press hard against their erring brothers, and aggravate their punishment.
Related Commentaries of 2 Chronicles 28:10
2 Chronicles 28:10
10 And now ye purpose to keep under the children of Judah and Jerusalem for bondmen and bondwomen unto you: but are there not with you, even with you, sins against the LORD your God?