Cursed [be] he that doeth the work of the Lord deceitfully,.... Which is said with respect to the Chaldeans, who were enjoined to destroy the Moabites; which is called the work of the Lord, because he had given them a commission to do it; and which was to be done by them, not by halves, or in a remiss and negligent manner, but fully and faithfully; they were not to spare them, as Saul did the Amalekites, and Ahab Benhadad.
This is a general rule, which may be applied to all divine work and service; every man has work to do for God; some in a more public, others in a more private way; all should be done in uprightness and sincerity, with all faithfulness and integrity: it is done deceitfully when men play the hypocrite; and negligently when they are backward to it, lukewarm in it, and infrequent in the performance of it; which brings upon them the curse of God; and which is not a curse causeless, but a legal one; and is no other than the wrath of God in strict justice:and cursed [be] he that keepeth back his sword from blood; from shedding the blood of the Moabites, when God had given command to do it.