A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
ch1 0:0THE FIRST AND SECOND BOOKS OF CHRONICLES were also considered as one by the ancient Jews, who called them "words of days," that is, diaries or journals, being probably compiled from those registers that were kept by the king's historiographers of passing occurrences. In the Septuagint the title given them is Paraleipomenon, "of things omitted," that is, the books are supplementary because many things unnoticed in the former books are here recorded; and not only the omissions are supplied, but some narratives extended while others are added. The authorship is commonly ascribed to Ezra, whose leading object seems to have been to show the division of families, possessions, &c., before the captivity, with a view to the exact restoration of the same order after the return from Babylon. Although many things are restated and others are exact repetitions of what is contained in Kings, there is so much new and important information that, as JEROME has well said, the Chronicles furnish the means of comprehending parts of the New Testament, which must have been unintelligible without them. They are frequently referred to by Christ and the Apostles as forming part of "the Word of God" (see the genealogies in Mat. 1:1-16; Luk. 3:23-38; compare Ch2 19:7 with Pe1 1:17; Ch2 24:19-21 with Mat 23:32-35).