Mishnà su Levitico 19:10

Beth Shammai says: [produce pronounced] ownerless with respect to the poor [only] is counted as ownerless. But Beth Hillel says: it is not counted as ownerless unless it is made ownerless also with respect to the rich, as in the year of release (shmittah). If all the sheaves of the field were of one kav each and one was of four kavs, and it was forgotten, Beth Shammai says: it does not count as forgotten, And Beth Hillel says: it counts as forgotten.

A vineyard of the fourth year Beth Shammai says: it is not subject to the law of the fifth nor to the law of removal. And Beth Hillel says: it is subject to the law of the fifth and to the law of removal. Beth Shammai says: it is subject to the law of fallen grapes and to the law of gleanings, and the poor redeem them for themselves. And Beth Hillel says: all of it goes to the winepress.

Two sheaves [left lying together] are “forgotten,” but three are not “forgotten.” Two bundles of olives or carobs are “forgotten” but three are not “forgotten.” Two flax-stalks are “forgotten”, but three are not “forgotten”. Two grapes are considered “grape gleanings,” but three are not “grape gleanings.” Two ears of grain are deemed “gleanings,” but three are not gleanings.” All these [rulings] are according to Bet Hillel. And concerning them all Bet Shammai says that three [that are left] belong to the poor, and four belong to the owner.