 Tractate Peah in the Mishnah, Tosefta, and Jerusalem Talmud interpreted the laws of the harvest of the corner of the field and gleanings to be given to the poor in and and 

The Mishnah taught that the Torah defines no minimum or maximum for the donation of the corners of one's field to the poor.But the Mishnah also taught that one should not make the amount left to the poor less than one-sixtieth of the entire crop.And even though no definite amount is given, the amount given should accord with the size of the field, the number of poor people, and the extent of the yield.