For Heshbon was the city of Sihon the king of the
Amorites,
&c.] His royal city, where he kept his palace, where he had
resided for some time, and perhaps some of his predecessors; and
therefore being now in his possession when taken by the
Israelites, they had a good right and title to keep it, and dwell
in it: and indeed this is here given as a reason of it,
who had fought against the former king of Moab;
either the king that reigned before Balak, or some king of Moab,
that reigned formerly, against whom one of the name of Sihon,
which might be a common name to the kings of the Amorites, as
Pharaoh to the Egyptians, had engaged in war:
and taken all his land out of his hand, even unto
Arnon;
and had been in the hands of the Amorites some years; and
therefore the Moabites had no reason to object to the Israelites
dwelling in it, and possessing it, which they had not taken from
them, but from the Amorites in a lawful war. And for proof of
this, reference is had to the bards and poets of those times, who
were the persons that transmitted in verse the history of famous
actions to posterity.