Parashas Behar · Aliyah 5 · Passuk 25:30
Chabad.org — English translation + Rashi
Torah Temimah cites Sifra / Arakhin 31a.
English: “Then the house… shall be established permanently.” This teaches that if it is not redeemed within the year, it is acquired as a permanent acquisition.
Classical derasha (Sifra / Bavli Arakhin).
Failure to redeem a house in a walled city within one year results in permanent transfer to the buyer; it does not revert at Yovel.