Rashi and Targum Yonasan: It is referring to a laborer ¹ (who is picking grapes in the vineyard). ²

Bava Metzi'a, 87b: It is a Binyan Av (a precedent). In fact, any laborer who is working with produce that grows from the ground, and who is performing a final task (such as harvesting) ¹ may eat from the fruit that he is working with (irrespective of whether he is working with his hands, his feet or his shoulders - Bava Metzi'a, 81b).

Bava Metzi'a, 87b: It precludes the vineyard of a Nochri (where a Jewish labborer is even permitted to place grapes into his basket) ¹ and a vineyard belonging to Hekdesh (from which he is forbidden to eat) whilst working.

Bava Metzi'a, 85b: The Torah writes "be'Kerem" - permitting him to eat even ihe has been hired to transport the picked grapes to the wine-press. ¹

Bava Metzi'a, 87b: It implies that he is permitted to eat the grapes, but not to suck them ¹ or to eat anything else together with them (or to peel figs and squeeze them on to the grapes - Yerushalmi Bava Metzi'a, 7:2). ²

Rambam, Hilchos S'chirus, 12:6: It confines the concession to eat them to eating the grapes - or the wheat-kernels - as they are, but not to bring his wife and children along to singe them in the oven for him to eat. ¹

Yerushalmi Ma'asros, 2:4: To teach us that if he is working in a vineyard he is allowed to eat grapes, but not figs, ² and vice-versa.

Rashi #1 and Targum Yonasan: "ke'Nafsh'cha" means 'to your heart's desire' - as much as you want, and "ke'Sav'echa" - until you are satiated - but not more.

Rashi: "ke'Nafsh'cha" means 'as if they belonged to you'.

Oznayim la'Torah: "ke'Nefsh'cha" is referring to someone who has eaten to satisfaction and who wants to eat something sweet as a dessert - for which there is lways room, ¹ whereas "Sav'echa" is refrerring to a laborer who arrives hungry, who is not permitted to eat up to satiation.

Rashi: It implies that the Pasuk is referring to the time of harvest, when one places the grapes that one picks into the owner's basket. ¹

Yerushalmi Ma'asros, 2:4: The implication "ve'el Kely'cha Lo Siten", 'Aval Atah Nosen le'Keilav shel Chavercha' teaches us that the Pasuk is referring to a laborer who is picking grapes.

Bava Metzi'a, 92b: By the same token, the laborer is not permitted to ask the overseer to give some grapes to his wife and children (even against what he would otherwise have eaten). ²

Rashi #1: It means that the laborer is permitted to eat as many grapes as he wants ("ke'Nafsh'cha") - to the point of satiation ("Sav'echa") but not to gorge himself. ¹

Rashi #2 (in Bava Metzi'a, 87b): "ke'Nafsh'cha" means 'as if they were yours'. You may eat without tithing (just like the owner is not obligated to tithe until he makes wine). ²

Yerushalmi Ma'asros, 2:4: "ke'Nafsh'cha" implies that he may eat whatever he wants - even to confine his eating to the best quality grapes. ³

Bava Metzi'a, 87b: It implies that he is permitted to eat as much as he wishes - to the point of satisfaction, evena Dinar's-worth, even though he was only hired to work for a silver Ma'ah (a fraction of a Dinar). ⁴

Bava Metzi'a, 88b #1: See previous answer. It implies that the laborer is only permitted to eat from what is detached if it has not yet reached the stage of G'mar Melachah for tithing. ⁵

Bava Metzi'a 88a #2: "ke'Nafsh'cha" means 'like yourself'. ⁶ To teach us that, just as if one would muzzle oneself, one would be Patur, so too is one Patur if one muzzles the laborer. ⁷

Yerushalmi Ma'asros, 2:4: "Sav'echa" teaches us that he is not permitted to vomit the grapes that he ate in order to eat more. ⁸