Jamieson, Fausset and Brown on Leviticus 25:23-28

23-28. The land shall not be sold for ever--or, "be quite cut off," as the Margin better renders it. The land was God's, and, in prosecution of an important design, He gave it to the people of His choice, dividing it among their tribes and families--who, however, held it of Him merely as tenants-at-will and had no right or power of disposing of it to strangers. In necessitous circumstances, individuals might effect a temporary sale. But they possessed the right of redeeming it, at any time, on payment of an adequate compensation to the present holder; and by the enactments of the Jubilee they recovered it free--so that the land was rendered inalienable. (See an exception to this law, Le 27:20).