John Gill Commentary Judges 9:35

"And Gaal the son of Ebed went out, and stood in the entrance of the gate of the city: and Abimelech rose up, and the people that were with him, from the ambushment." — Judges 9:35 (ASV)

And Gaul the son or Ebed went out
He rose up early that morning, being a man of vigilance and activity, and perhaps had some intelligence of the preparations of Abimelech, his design against the city, though he did not expect he was so near at hand:

and stood in the entering of the gate of the city ;
to see whether the guards were on their duty within, and whether he could observe any thing without, any approaching danger:

and Abimelech rose up, and the people that were with him, from lying in
wait ;
came out of their ambush, and appeared just as Gaul was at the gate.