C. F. Keil and Franz Delitzsch on Jeremiah 6:17

Jer 6:17

But God does not let the matter end here. He caused prophets to rise up amongst them, who called their attention to the threatening evil. Watchers are prophets, Eze 3:17, who stand upon the watch-tower to keep a lookout, Hab 2:1, and to give the people warning, by proclaiming what they have seen in spirit. "Hearken to the sound," etc., are not the words of the watchmen (prophets), for it is they who blow the trumpet, but the words of God; so that we have to supply, "and I said." The comparison of the prophets to watchmen, who give the alarm of the imminent danger by means of the sound of the trumpet, involves the comparison of the prophets’ utterances to the clang of the signal-horn-suggested besides by Amo 3:6.