Unknown Author
Judges 4:21ESV·author unknown

But Jael the wife of Heber took a tent peg, and took a hammer in her hand. Then she went softly to him and drove the peg into his temple until it went down into the ground while he was lying fast asleep from weariness. So he died.

Matthew Henry Presbyterian @wholebiblehenry

We have seen the army of the Canaanites totally routed. It is said (Psa 83:9, Psa 83:10, where the defeat of this army is pleaded as a precedent for God's doing the like in after times) that they became as dung for the earth. Now here we have, I.

Commenting on Judges 4:17-24

John Gill Reformed Baptist @doctorgill

Then Jael, Heber's wife, took a nail of the tent,.... When she perceived he was fast asleep, and it being now put into her heart to kill him, having an impulse upon her spirit, which she was persuaded, by the effect it had upon her, that it was of God; not filling her with malice and revenge, but a concern for the glory of God...

Jamieson-Fausset-Brown Reformed @jfbcommentary

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.