Charles Ellicott Commentary Leviticus 19:10

"And thou shalt not glean thy vineyard, neither shalt thou gather the fallen fruit of thy vineyard; thou shalt leave them for the poor and for the sojourner: I am Jehovah your God." — Leviticus 19:10 (ASV)

And you shall not glean your vineyard. —When harvesting the vine, care should be taken only to cut off the large clusters, but not the infantas, as the expression literally denotes, which is here rendered as “glean.” Those branches or twigs which had only one or two grapes on them were to be left to the poor.

Nor shall you gather every grape. —Better, Nor shall you gather the scattered grapes, that is, those single grapes which had either fallen to the ground during the process of cutting off the branches, or those which were scattered about the ground after the vintage was completed. Like the gleanings of the field, these grapes were the portion of the poor, both of Jewish origin and proselytes.