18 Yahweh said to Joshua, “Stretch out the javelin that is in your hand toward Ai, for I will give it into your hand.”
Joshua stretched out the javelin that was in his hand toward the city. 19 The ambush arose quickly out of their place, and they ran as soon as he had stretched out his hand, and entered into the city, and took it. They hurried and 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.