Then said Zebul, Where is now thy mouth, &c. Now show thyself a man, and fight valiantly for thyself and the people. And he fled Being surprised by the unexpected coming of Abimelech, and probably not fully prepared for the encounter.
Related Commentaries of Judges 9:38
Judges 9:38-40
38 Then said Zebul unto him, Where is now thy mouth, wherewith thou saidst, Who is Abimelech, that we should serve him? is not this the people that thou hast despised? go out, I pray now, and fight with them.
39 And Gaal went out before the men of Shechem, and fought with Abimelech.
40 And Abimelech chased him, and he fled before him, and many were overthrown and wounded, even unto the entering of the gate.