The Torah in Parashat Kedoshim (Vayikra 19:10) requires leaving certain portions of one’s agricultural produce for the poor, including “Olelot,” to which the Sefer Ha’hinuch refers as “Pe’at Ha’kerem” (literally, “the corner of the vineyard”).
This obligation, which applies specifically to the produce of vineyards, parallels the Misva of Pe’a, which requires leaving the corner of one’s field for the poor. However, unlike the obligation of Pe’a, the obligation of “Pe’at Ha’kerem” does not require leaving a specific area of the vineyard. Rather, as the Rambam explains, it requires leaving behind the clusters of grapes that remain after the harvest. When a vineyard is harvested, it is likely that some smaller clusters will be left unharvested by the workers. The Torah commands that instead of returning to the vineyard to harvest these remaining grapes, they must instead be left for the poor. Just as one who grows other produce must leave the corner of his field for the poor, so must the owner of a vineyard leave behind the clusters which were forgotten during the grape harvest.