Charles Ellicott Commentary Jeremiah 26:18

"Micah the Morashtite prophesied in the days of Hezekiah king of Judah; and he spake to all the people of Judah, saying, Thus saith Jehovah of hosts: Zion shall be plowed as a field, and Jerusalem shall become heaps, and the mountain of the house as the high places of a forest." — Jeremiah 26:18 (ASV)

Micah the Morasthite. —On the general history and work of this prophet, see Introduction to Micah. The Hebrew text gives Micaiah, the two forms being interchangeable in Hebrew (as in Judges 17:1 and 17:4, compare with Judges 17:5 and 17:12). The epithet indicated his birth in Moresheth-gath in Philistia (Micah 1:14). As Micah had prophesied under Jotham and Ahaz (Micah 1:1), the prediction here referred to must have been delivered towards the close of his ministry.

The words cited are from Micah 3:12, and immediately precede the prediction of an ultimate restoration of Judah in the last days in Micah 4:1-2, which we find in identical terms in Isaiah 2:2-3. Here, then, was a case—this is the implied argument of the elders—in which a threat did its work, and therefore was not fulfilled. It did good, and not evil. The phrase “mountain of the house” is not found elsewhere in Jeremiah as a description of the Temple.