56 Thus God repaid the wickedness that Abimelek had done to his father by murdering his seventy brothers.

Read Judges 9:56 Using Other Translations

Thus God rendered the wickedness of Abimelech, which he did unto his father, in slaying his seventy brethren:
Thus God returned the evil of Abimelech, which he committed against his father in killing his seventy brothers.
In this way, God punished Abimelech for the evil he had done against his father by murdering his seventy brothers.