Charles Ellicott Commentary Jeremiah 48:10

"Cursed be he that doeth the work of Jehovah negligently; and cursed be he that keepeth back his sword from blood." — Jeremiah 48:10 (ASV)

Cursed be he ... —To the prophet the destruction of the tyrannous haughtiness was a righteous retribution in which he saw the work of Jehovah, and he could not wish that it should be done otherwise than effectually.

This thought rests on the belief in the Divine government that works through war as well as through pestilence and famine (Jeremiah 25:31; Jeremiah 46:10). (Compare like utterances in Judges 5:23; 1 Samuel 15:3; 1 Samuel 15:18; 1 Kings 20:42.)

Even Christian nations fighting against slave-traders or pirates might legitimately echo the same prayer. It has been used, with less justification, in the religious wars of our own and other countries.