Matthew Henry Presbyterian @wholebiblehenry

Here is, I. The general character of Amaziah: He did that which was right in the eyes of the Lord, worshipped the true God, kept the temple service a going, and countenanced religion in his kingdom; but he did not do it with a perfect heart (Ch2 25:2), that is, he was not a man of serious piety or devotion himself, nor had he any...

Commenting on 2 Chronicles 25:1-13

Geneva Bible Notes Reformed @genevanotes

And he did [that which was] right in the sight of the LORD, but not with a perfect heart. (a) Meaning, in respect to his predecessors, though he had his imperfections.

Adam Clarke Methodist @methodicalclarke

He did that which was right - He began his reign well, but soon became an idolater, Ch2 25:14, Ch2 25:15.