Judges 9:18
And ye are risen up against my father’s house this day, and have slain his sons, threescore and ten persons, upon one stone, and have made Abimelech, the son of his maidservant, king over the men of Shechem, because he is your brother;) And ye are risen up against my father’s house this day, and have slain his sons, threescore and ten persons, upon one stone, and have made Abimelech, the son of his maidservant, king over the men of Shechem, because he is your brother;)
The verse belongs to Jotham's charge that the people of Shechem had risen up that day against his father's house. Seventy sons of Gideon, Abimelech's own brothers, had been murdered upon one stone at Abimelech's instigation. The men of Shechem then made Abimelech, Gideon's son by a maidservant and their own kinsman, king over them because he was their brother. He had those sons slain in order to make himself ruler of Israel over the men of Shechem. He afterward utterly destroyed Shechem itself, a very ancient place where Jacob had stopped on returning from Padan-aram to Canaan.
Backing his violent seizure of power laid bare the ingratitude and injustice of the Shechemites toward Gideon's family. To set over themselves as king a man guilty of killing his seventy brothers was folly. Though called the son of a maidservant, Abimelech was free just as his brothers were and was eligible to be made king, for his mother's standing did not make her or her children slaves.
The wider chapter is a parable, teaching its lesson by an imaginary scene of trees holding a council and speaking, not by recounting things that actually took place. In the same manner the stone is set forth as hearing and witnessing words spoken before it, showing that Scripture may personify an inanimate thing as speaking or acting without meaning that it is conscious.