C. F. Keil and Franz Delitzsch on Judges 9:32-33

Jdg 9:32-33

At the same time he called upon Abimelech to draw near, with the people that he had with him, during the night, and to lie in wait in the field (ארב, to place one’s self in ambush), and the next morning to spread out with his army against the town; and when Gaal went out with his followers, he was to do to him “as his hand should find,” i.e., to deal with him as he best could and would under the circumstances. (On this formula, see at 1Sa 10:7; 1Sa 25:8.)