The inhabitants of Meroz (a village 12 miles from Samaria) hung back, and gave no help in the day of battle, although it was Yahweh who called them. Hence, the curse pronounced by the Angel of the Lord.
Related Commentaries of Judges 5:23
Judges 5:23
23 Curse ye Meroz, said the angel of the LORD, curse ye bitterly the inhabitants thereof; because they came not to the help of the LORD, to the help of the LORD against the mighty.