Charles Ellicott Commentary 2 Chronicles 35:26

"Now the rest of the acts of Josiah, and his good deeds, according to that which is written in the law of Jehovah," — 2 Chronicles 35:26 (ASV)

His goodness. That is, His pious deeds (2 Chronicles 32:32).

According to that ... the Lord. This was said of no king besides.

The book ... and Judah. See 2 Kings 23:28: the Book of the chronicles of the kings of Judah.