24 And it came to pass when Israel had made an end of slaying all the inhabitants of Ai in the field, in the wilderness where they pursued them, and when they all had fallen by the edge of the sword until they were consumed, that all the Israelites returned to Ai and struck it with the edge of the sword.
Matthew Henry's Commentary on Joshua 8:24
Commentary on Joshua 8:23-29
(Read Joshua 8:23-29)
God, the righteous Judge, had sentenced the Canaanites for their wickedness; the Israelites only executed his doom. None of their conduct can be drawn into an example for others. Especial reason no doubt there was for this severity to the king of Ai; it is likely he had been notoriously wicked and vile, and a blasphemer of the God of Israel.