Jamieson, Fausset and Brown on Judges 5:15

15. Then comes a reproachful notice of the tribes which did not obey the summons to take the field against the common enemy of Israel. By the

divisions--that is, the watercourses which descend from the eastern hills unto the Jordan and Dead Sea.

For the divisions of Reuben there were great thoughts of heart--They felt the patriotic impulse and determined, at first, to join the ranks of their western brethren, but resiled from the purpose, preferring their peaceful shepherd songs to the trumpet sound of war.