18 Then the Lord said to Joshua, "Stretch out the sword that is in your hand toward Ai; for I will give it into your hand." And Joshua stretched out the sword that was in his hand toward the city. 19 As soon as he stretched out his hand, the troops in ambush rose quickly out of their place and rushed forward. They entered the city, took it, and at once set the city 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.