18 Then the Lord said to Joshua, "Point the spear in your hand toward Ai, for I will hand the town over to you." Joshua did as he was commanded. 19 As soon as Joshua gave this signal, all the men in ambush jumped up from their position and poured into the town. They quickly captured it and set it on fire.
Matthew Henry's Commentary on Joshua 8:18-19
Commentary on Joshua 8:3-22
(Read Joshua 8:3-22)
Observe Joshua's conduct and prudence. Those that would maintain their spiritual conflicts must not love their ease. Probably he went into the valley alone, to pray to God for a blessing, and he did not seek in vain. He never drew back till the work was done. Those that have stretched out their hands against their spiritual enemies, must never draw them back.