Upon one stone— It has been conjectured from this by some, that Abimelech intended to make his brethren a great victim to Baal; for a stone was sometimes used for an altar, 1 Samuel 6:14-15.; and so they take this to be done in revenge of the sacrifice of the bullock prepared for Baal, chap. Judges 6:25-26. Which crime of Gideon, as these idolaters account it, they designed to expiate by the sacrifice of all his sons.
Related Commentaries of Judges 9:5
Judges 9:5
5 And he went unto his father's house at Ophrah, and slew his brethren the sons of Jerubbaal, being threescore and ten persons, upon one stone: notwithstanding yet Jotham the youngest son of Jerubbaal was left; for he hid himself.