Judges 9:25
And the men of Shechem set liers in wait for him in the top of the mountains, and they robbed all that came along that way by them: and it was told Abimelech. And the men of Shechem set liers in wait for him in the top of the mountains, and they robbed all that came along that way by them: and it was told Abimelech.
Shechem was a very ancient place where Jacob stopped on his return from Padan-aram to Canaan, and it was later utterly destroyed by Abimelech. Abimelech was the son of Gideon's maidservant, and he had Gideon's sons killed so that he himself might become ruler of Israel. The men of Shechem chose him as ruler despite his murder of his brothers. The verse belongs to the broader record of Israel's backsliding from God and the resulting suffering, oppression, and servitude.
The ambush marks the beginning of divine retribution after Abimelech's three-year reign, when the Lord sent trouble among those united in evil. The very men of Shechem who had made Abimelech king became disgusted with his demoralizing rule and heartless tyranny and opposed him. They set liers in wait for him and determined by treachery to remove him as he had by treachery gained the throne. Their hostility and ambush fulfilled the words of Jotham, with discord, strife, and hatred prevailing between Abimelech and his subjects. This brought the time of punishment for both Abimelech and the Shechemites who had sustained him, showing that sin will never go unpunished.
The trees in Judges 9 that hold a council and speak to one another are imaginary figures used to teach a lesson, not a literal account of trees that spoke. Jotham's parable of the trees teaches that those doing the most valuable work for the Lord have no desire to rule over their brethren. Ambition to be exalted over others shows a person is wholly unfit to rule.