Compare Deuteronomy 21:22-23 notes.

The king of Ai he hanged on a tree - He had gone out at the head of his men, and had been taken prisoner, Joshua 8:23; and the battle being over, he was ordered to be hanged, probably after having been strangled, or in some way deprived of life, as in the case mentioned Joshua 10:26, for in those times it was not customary to hang people alive.

As soon as the sun was down - It was not lawful to let the bodies remain all night upon the tree. See the note on Deuteronomy 21:23. The Septuagint say the king of Ai was hanged επι ξυλον διδυμον, upon a double tree, which probably means a forked tree, or something in the form of a cross. The tree on which criminals were hanged among the Romans was called arbor infelix, and lignum infelix, the unfortunate, ill-fated, or accursed tree.

Raise thereon a great heap of stones - This was a common custom through all antiquity in every country, as we have already seen in the case of Achan, Joshua 7:20.

And the king of Ai he hanged on a tree until eventide,.... By way of terror to other kings in the land of Canaan, that should refuse to submit unto him:

and as soon as the sun was down, Joshua commanded that they should take his carcass down from the tree; according to the law in Deuteronomy 21:23; and that the land might not be defiled:

and cast it at the entering of the gate of the city; this was done, according to Ben Gersom and Abarbinel, that it might be publicly known to the rest of the kings of the nations, that they might be afraid to fight with Israel:

and raise thereon a great heap of stones, that remaineth unto this day; as a sepulchral monument, showing that there was a person lay interred there; whether there was any inscription on the stone, showing who he was, does not appear; it looks as if it was only a rude heap of stones; and such kind of sepulchral monuments were common in former times in other countries.

He had the king of Ai hanged upon a tree, i.e., put to death, and then suspended upon a stake (see Numbers 25:4) until the evening; but at sunset he had him taken down (in accordance with Deuteronomy 21:22-23), and thrown at the entrance of the town-gate, and a heap of stones piled upon him (as in the case of Achan, Joshua 7:26).

And the king of Ai he hanged on a tree until eventide: and as soon as the sun was down, Joshua commanded {m} that they should take his carcase down from the tree, and cast it at the entering of the gate of the city, and raise thereon a great heap of stones, that remaineth unto this day.

(m) According as it was commanded, De 21:23.

8:29 Hanged on a tree - He dealt more severely with the kings of Canaan than with the people, because the abominable wickedness of that people was not restrained and punished (as it should have been) but countenanced and encouraged by their evil examples; and because they were the principal authors of the destruction of their own people, by engaging them in an obstinate opposition against the Israelites. Down from the tree - According to God's command in that case, Deut 21:22. The gate of the city - Which place he chose either as most commodious, now especially when all the city within the gate was already turned in to an heap of stones and rubbish; or because this was the usual place of judgment; and therefore proper to bear the monument of God's just sentence against him, not without reflection upon that injustice which he had been guilty of in that place.

Jos 8:29. The King Hanged.

29. The king of Ai he hanged on a tree until eventide-that is, gibbeted. In ancient, and particularly Oriental wars, the chiefs, when taken prisoners, were usually executed. The Israelites were obliged, by the divine law, to put them to death. The execution of the king of Ai would tend to facilitate the conquest of the land, by striking terror into the other chiefs, and making it appear a judicial process, in which they were inflicting the vengeance of God upon His enemies.

take his carcass down . and raise thereon a great heap of stones-It was taken down at sunset, according to the divine command (De 21:23), and cast into a pit dug "at the entering of the gate," because that was the most public place. An immense cairn was raised over his grave-an ancient usage, still existing in the East, whereby is marked the sepulchre of persons whose memory is infamous.

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.