Halakha Ulangan 24:20: Mishneh Torah, Gifts to the Poor, Mishneh Torah, Negative Mitzvot & Sefer HaChinukh

Just as it is with forgotten sheaves [shikhecha, the "forgotten"], so it is with standing grain. If one has forgotten a portion of standing grain, one may not harvest it. It is for the poor. And just as with forgotten produce and their products, so also with forgotten fruit of trees altogether, as it is said, (Deut. 24:20) When you beat down the fruit of your olive trees, do not go over them again. So it applies to all other types of trees.⁴With regard to trees, however, there are exceptions, such as with carob trees. See 3:21.

Not to return to take a forgotten sheaf, as it is said, (“When thou reapest thy harvest) and hast forgotten a sheaf in the field, thou shalt not go again to fetch it” (Deut. 24:19). This applies to all fruit trees, as it is said, “Thou shalt not go over the boughs again” (ibid. 24:20).

To not finish the corner of the vineyard: To not finish all of the fruit of the vineyard at the time of the grape harvest, but [rather, one] leaves a corner from them to the poor, as it is stated (Leviticus 19:10), “And [in] your vineyard, you shall not take the bunchless grapes” — this is the corner of the vineyard. So wrote Rambam, may his memory be blessed. And he said further that, that which is written (Deuteronomy 24:20), “you shall not take from the branchlets after you” with olives, also instructs about the corner of the olive tree. As the corner of the olive trees is called branchlets (porot), and the corner of the vineyard is called bunchless grapes (ollalot). And from the both of them we learn [this] for all the trees. And Ramban, may his memory be blessed, argued against him about this and said (in his introduction to the details of the commandments) that it is all a mistake. And he said that the negative commandment of “And [in] your vineyard,” is unique specifically to the vineyard — and it is that we leave over all of the small grapes in it that do not have a katef or a natef. And the understanding of katef is sprigs one over the other (clusters); [of] natef is that they all hang and descend. And it comes out according to this that the ollalot are the small grapes sometimes found in the vineyard that are called gatimas in the vernacular. And this is certainly a small thing, according to that which we see in our vineyards. And so did they, may their memory be blessed say (Mishnah Peah 7:4), “Which are ollalot? All that do not have a katef nor a natef.”