judges 4:21 Then Jael Heber's wife took a nail of the tent, and took an hammer in her hand, and went softly unto him, and smote the nail into his temples, and fastened it into the ground: for he was fast asleep and weary. So he died. - Free Bible Online

      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.

JFB.