John Gill Commentary Deuteronomy 13:12

"If thou shalt hear tell concerning one of thy cities, which Jehovah thy God giveth thee to dwell there, saying," — Deuteronomy 13:12 (ASV)

If you shall hear say in one of your cities
A report concerning them, anyone of them:

which the Lord your God had given you to dwell there ;
which he had not only given them, but had put them into the possession of, and it was become their dwelling place, or was inhabited by Israelites;

otherwise they were already given unto them, but did not inherit and inhabit them, and it might be possible that there might be some city or cities, at least for a time, which, though given them, were not inhabited by them, but by the Canaanites, and such cities this law did not concern: saying; as follows.