פירוש על קידושין 76:2

The reason that the R. Elazar had to state that the release from debt is observed outside of the Land is that there is some connection between this mitzvah and the land, since Rabbi connected it to the release of the land (the prohibition of working the land during the sabbatical year). Rabbi says that as long as the mitzvah of letting the land rest is observed, the mitzvah of release from debt is observed in all places. In other words, release of debt is observed outside the Land even though it is tied to the Land.