Negative commandment · Lo Ta’aseh #212 of 613
Not to harvest underdeveloped grape clusters
שלא לבצור עוללות הכרם
The verse · Vayikra 19:10
וְכַרְמְךָ לֹא תְעוֹלֵל וּפֶרֶט כַּרְמְךָ לֹא תְלַקֵּט לֶעָנִי וְלַגֵּר תַּעֲזֹב אֹתָם אֲנִי ה׳ אֱלֹהֵיכֶם
“And thou shalt not glean thy vineyard, neither shalt thou gather the single grapes of thy vineyard; thou shalt leave them for the poor and stranger: I am the Lord your God.”
The Rambam’s words
Not to harvest underdeveloped grape clusters, as [Leviticus 19:10] states: "Do not pick the incompletely formed grape clusters in your vine-yard."
שלא לבצור עוללות הכרם, שנאמר "וכרמך לא תעולל" (ויקרא יט,י).
Why · Sefer HaChinuch #221
To not finish the corner of the vineyard
“It is from the roots of the commandment that G-d, blessed be He, wanted that His people that He chose be crowned with every good and dear trait and that they would have a blessed soul and a generous spirit.”
Who & when
“And there, it is written in which place it and all of the other gifts to the poor are practiced, and that the details of the commandment of the corner are elucidated in Tractate Peah.”
Where in the Mishneh Torah
Hilchot Gifts to the Poor הלכות מתנות עניים