When Zebul the governor of the city heard what Gaal son of Ebed said, he was very angry.
Under cover he sent messengers to Abimelech, saying, "Gaal son of Ebed and his brothers have come to Shechem and are stirring up the city against you.
Now then, during the night you and your men should come and lie in wait1 in the fields.
References for Judges 9:32
In the morning at sunrise, advance against the city. When Gaal and his men come out against you, do whatever your hand finds to do.2"
References for Judges 9:33