Jamieson, Fausset and Brown on Jeremiah 6:4-5

4-5. The invading soldiers encourage one another to the attack on Jerusalem.

Prepare--literally, "Sanctify" war, that is, Proclaim it formally with solemn rites; the invasion was solemnly ordered by God (compare Is 13:3).

at noon--the hottest part of the day when attacks were rarely made (Jr 15:8; 20:16). Even at this time they wished to attack, such is their eagerness.

Woe unto us--The words of the invaders, mourning the approach of night which would suspend their hostile operations; still, even in spite of the darkness, at night they renew the attack (Jr 6:5).