His brethren — The only persons who were likely to hinder him in establishing his tyranny. Threescore and ten — Wanting one, who is here expressed. Jotham was left — Whereby he would signify, that this was an act of justice, in cutting them all off in an orderly manner, for some supposed crime, probably, as designing sedition and rebellion.
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.