Rashi: It is a La'av forbidding purchasers to retain the fields that they bought when Yovel arrives. ¹

Ramban #1 and Moshav Zekenim #1 (both citing the Rambam): It is a La'av forbidding the seller or the purchaser to stipulate that he is selling or buying the field permanently. ²

Ramban #2 and Moshav Zekenim #2 (both citing the the Sifra): It is a Mitzvah to keep the Yovel among yourselves, and don't be upset about it, since the land belongs to Me and I don't want it to be sold permanently like other sales'. ³

Bava Metzi'a, 79a: The Pasuk implies that only a sale that, were it not for Yovel would be permanent, ⁴ goes back in the Yovel, but that if one sold the field, for example, for sixty years, the field does not go back in the Yovel. ⁵

Rashi, Targum Onkelos and Targum Yonasan: It is a prohibition against selling one's field permanently. ¹

Rashi: It means that one should not begrudge having to return the field, since it is not his anyway.

Seforno: It means that Eretz Yisrael is the land of Hashem. ¹

Gitin, 47a: It means that the Kedushah of the Eretz Yisrael belongs to Hashem and that consequetly, a Nochri who purchases land there does not remove the obligation to take Ma'asros from its produce. ²

Rashi (in Divrei Hayamim 1, 29:15): It implies that we have no portion, inheritance or possession in the land other than the right to sojourn in it. ¹

Ramban (citing the Sifra): It means 'Don't consider yourselves the main owners of your field; because you are with Me'. ²

Seforno: Refer to 35:23:3:2*.