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. (Judges 9:5)
Like sacrificial beasts (1 Sam. 14:33-35), Abimelech slew his brothers, perhaps on the rock on which Gideon had built his altar.
Slew his brethren.
This was the usual way of usurpers in securing their throne; the person who had no right destroyed all those who had right, so that he might have no competitors. Despots anticipated conspiracies, and so destroyed all their brothers and near kinsmen.
Jotham.
Literally, “the Lord is perfect.” That Gideon would give such a name to his 70th son indicates that he remained a loyal believer in the Lord despite the ephod he had made.