Charles Ellicott Commentary Jeremiah 40:8

"then they came to Gedaliah to Mizpah, [to wit], Ishmael the son of Nethaniah, and Johanan and Jonathan the sons of Kareah, and Seraiah the son of Tanhumeth, and the sons of Ephai the Netophathite, and Jezaniah the son of the Maacathite, they and their men." — Jeremiah 40:8 (ASV)

Then they came to Gedaliah. — Of the captains thus named, Ishmael, of the seed royal (we have no information for determining his precise position in the line of successors) (Jeremiah 41:1), is prominent in the history of the next chapter; Johanan (the Hebrew form of Joannes or John) is prominent in that of Jeremiah 42; Seraiah and Jaazaniah are named in the parallel passage of 2 Kings 25:23, but nothing more is known of them.

Netophah, to which the sons of Ephai belonged, was a town of Benjamin not far from Bethlehem (1 Chronicles 2:54; 1 Chronicles 9:16; Ezra 2:22; Nehemiah 7:26). The Maachathite, whose father is not named, was probably a naturalised alien from the small kingdom of Maachah, on the east side of the Jordan, near Argob (Deuteronomy 3:14; 2 Samuel 10:6; 2 Samuel 10:8) and Bashan (Joshua 12:5), not far from the modern Lejah.