18 Then the Lord said to Joshua, "Stretch out the spear that is in your hand toward Ai, for I will give it into your hand." And Joshua stretched out the spear that was in his hand toward the city. 19 So those in ambush arose quickly out of their place; they ran as soon as he had stretched out his hand, and they entered the city and took it, and hurried to 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.