Charles Ellicott Commentary Jeremiah 10:21

"For the shepherds are become brutish, and have not inquired of Jehovah: therefore they have not prospered, and all their flocks are scattered." — Jeremiah 10:21 (ASV)

The pastors. —The “shepherds,” used, as in Jeremiah 2:8; Jeremiah 3:15, and elsewhere, of rulers generally, rather than of priests as such.

Therefore they shall not prosper. —Better, therefore they have not done wisely. This is the primary meaning of the word (that of prosperity, as the result of prudence, is the secondary), and is adopted by the Septuagint, Vulgate, and most other versions.

All their flocks. —Literally, all their pasture, the place, or the act, of pasturing, taken practically for the sheep that fed on it.