Oznayim la'Torah: To teach us that it is not only because we were Geirim in Egypt that we should not oppress a Ger, but because even now, he is in no way inferior to us. See how we too are Geirim in the land - which belongs to Hashem, as is evident from the fact that, once every seven years we are obligated to leave the land fallow in honor of its true Master.

Rashi and Targum Yonasan: It means 'You know how the stranger suffers (when he is oppressed - Rashi)'.

Mechilta: To teach us that that is what will happen if Yisrael perform the will of Hashem - whereas if they don't, they will plow one year and plant the next year - so that they will in effect, have to observe four Sh'mitos in each seven-year cycle. ¹

R. Bachye: Because, whereas after Sh'mitah has passed, the field and the vineyard goes back to the owner, ¹ in Yovel, the land goes back to Hashem ? its true Owner ? and after Yovel, a new era begins. ²

Da'as Zekenim: It implies that it is a Mitzvah to plant in the Sh'mitah. A Midrash teaches us that, even if one owns a small ruin in his garden, he must tend to it every day. ¹