משנה על פאה 6:1

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.