4:17-24 Sisera's chariots had been his pride and his confidence. Thus are those disappointed who rest on the creature; like a broken reed, it not only breaks under them, but pierces them with many sorrows. The idol may quickly become a burden, Isa 46:1; what we were sick for, God can make us sick of. It is probable that Jael really intended kindness to Sisera; but by a Divine impulse she was afterwards led to consider him as the determined enemy of the Lord and of his people, and to destroy him. All our connexions with God's enemies must be broken off, if we would have the Lord for our God, and his people for our people. He that had thought to have destroyed Israel with his many iron chariots, is himself destroyed with one iron nail. Thus the weak things of the world confound the mighty. The Israelites would have prevented much mischief, if they had sooner destroyed the Canaanites, as God commanded and enabled them: but better be wise late, and buy wisdom by experience, than never be wise.
21. Then Jael took a nail of the tent—most probably one of the pins with which the tent ropes are fastened to the ground. Escape was almost impossible for Sisera. But the taking of his life by the hand of Jael was murder. It was a direct violation of all the notions of honor and friendship that are usually held sacred among pastoral people, and for which it is impossible to conceive a woman in Jael's circumstances to have had any motive, except that of gaining favor with the victors. Though predicted by Deborah [Jud 4:9], it was the result of divine foreknowledge only—not the divine appointment or sanction; and though it is praised in the song [Jud 5:24-27], the eulogy must be considered as pronounced not on the moral character of the woman and her deed, but on the public benefits which, in the overruling providence of God, would flow from it.