Albert Barnes Commentary Jeremiah 6:17

"And I set watchmen over you, [saying], Hearken to the sound of the trumpet; but they said, We will not hearken." — Jeremiah 6:17 (ASV)

Watchmen - The prophets (Isaiah 52:8).

The second of the trumpet - This was the signal for flight (Jeremiah 6:1; Amos 3:6). Similarly the prophet’s warning was to move men to escape from God’s judgments.