Albert Barnes Commentary Jeremiah 29:3

"by the hand of Elasah the son of Shaphan, and Gemariah the son of Hilkiah, (whom Zedekiah king of Judah sent unto Babylon to Nebuchadnezzar king of Babylon,) saying," — Jeremiah 29:3 (ASV)

Elasah - Probably brother of Ahikam (Jeremiah 26:24), and therefore an acceptable person at the Chaldaean court. As Zedekiah had to go in person to Babylon in his fourth year (Jeremiah 51:59), this embassy was probably sent two or three years earlier. Its date, however, was subsequent to the vision in (Jeremiah 24:1–10). It is appended therefore to (Jeremiah 28:0), not as later in point of time, but because of the similarity of subject.