Then the LORD said to Joshua, “Hold out toward Ai the javelin that is in your hand, for into your hand I will deliver the city.” So Joshua held out toward the city the javelin that was in his hand. As soon as he did this, the men in the ambush rose quickly from their position and rushed forward. They entered the city and captured it and quickly set it on fire. The men of Ai looked back and saw the smoke of the city rising up into the sky, but they had no chance to escape in any direction; the Israelites who had been fleeing toward the wilderness had turned back against their pursuers. For when Joshua and all Israel saw that the ambush had taken the city and that smoke was going up from it, they turned around and attacked the men of Ai. Those in the ambush also came out of the city against them, so that they were caught in the middle, with Israelites on both sides. Israel cut them down, leaving them neither survivors nor fugitives. But they took the king of Ai alive and brought him to Joshua. – Joshua 8:18-23
Adolph Harstad writes:
A the critical moment in the battle when Ai and Bethel are left undefended, it is time for a special signal. The LORD Himself commands Joshua to reach out toward Ai with his javelin in his hand. Once more it is clear that the LORD is in charge. He is orchestrating the battle. It will be His victory. … Joshua is the earthly commander of the LORD’s host. When Joshua stretches out his hand according to God’s word, this indicates that at the same time the LORD Himself is also reaching out His almighty hand in judgment against the unbelieving Canaanites, as depicted in many other Old Testament passages. This action by God’s minister dramatizes in a concrete way the same dynamic that is in the office of the keys administered by pastors in the New Testament era:
If you forgive the sins of any, they are forgiven to them; if you retain [the sins] of any, they are retained (John 20:23).
… A parallel to Joshua holding out the javelin was the scene of Moses holding up his hands for Israel’s victory over the Amalekites in Exodus 17:10-13. Joshua holds the position that the great Moses once held. He deserves the respect and obedience once given Moses. The LORD is continuing to exalt Joshua in the eyes of Israel.
MEMORY WORK – Shorter Catechism Q/A 44
Q. 44. What doth the preface to the ten commandments teach us?
A. The preface to the ten commandments teacheth us that because God is the Lord, and our God, and redeemer, therefore we are bound to keep all his commandments.