Exodus 23:11

but the seventh year thou shalt let it rest and lie still, let it remain unused, make no attempt to cultivate it, that the poor of thy people may eat, namely, that produced by the land without cultivation, the so-called volunteer grain; and what they leave the beasts of the field shall eat. This fallowing of the land would give it an opportunity to recuperate. In like manner thou shalt deal with thy vineyard and with thy oliveyard. There also the fruits were not to be gathered, but left for the poor and needy, for the beasts of the field, and for the fowls of the air. This was the so-called Sabbath of Years, analogous to the Sabbath of the Week.