And he smote his enemies in the hinder part - From behind; that is, as they fled. There are two ideas here: one, that they fled at his approach, or turned their backs; the other, that as they fled, he smote and destroyed them.
He put them to a perpetual reproach - As discomfited; as defeated and scattered; as unable to contend with him. The allusion is, probably, to the victories of David, occurring after the events related in the preceding verses.