Charles Ellicott Commentary 1 Chronicles 6:39

"And his brother Asaph, who stood on his right hand, even Asaph the son of Berechiah, the son of Shimea," — 1 Chronicles 6:39 (ASV)

His brother Asaph. Asaph was Heman’s brother in two respects:

1. as a Levite;
2. as a choirmaster.

The striking agreement of the line of Heman with that of the Kohathites, detailed in 1 Chronicles 6:22–28 above, has led critics to look for a like coincidence between the line of Asaph as given here and that of the Gershonites in 1 Chronicles 6:20–21. In the Gershonite list, however, there are only seven names, while in Asaph's list, there are thirteen.

Still, we observe that in the former passage, the three names Jahath, Zimmah, and Zerah appear in the same order of lineal descent from Gershon as in the present list. Furthermore, the Adaiah of 1 Chronicles 6:41 obviously corresponds to the Iddo of 1 Chronicles 6:21, and Ethni (1 Chronicles 6:41) is, in Hebrew writing, not unlike Jeaterai.

We are already familiar with the fact that genealogies sometimes recur in abbreviated forms (compare Ezra 7:1-5 with the line of Aaron in this chapter). On the whole, therefore, if these suggested identifications are correct, it appears that Asaph’s pedigree has indeed been partially anticipated in 1 Chronicles 6:20–21.