Judges 9:56

‘ Thus God requited the wickedness of Abimelech which he did to his father, in killing his seventy brothers.’

God had avenged the hurt done to His servant Gideon by the killing of his sons, for He takes note of what is done to those who serve Him faithfully, and what Abimelech had done had removed Gideon’s heirs and had been an attempt to prevent the carrying on of his true line.