Bava Metzia 93 - Dealing in Food Entitlement
The produce that the worker eats while harvesting is a charitable gift from Heaven, not a fringe benefit of his work, and therefore he cannot assign it to his wife and children.
Instead, he may promise to not eat from harvested produce, in exchange for higher wages. He may also stipulate this for his adult children and his wife since they understand the deal and agree to it.
So they are giving up on the food for the sake of the benefit.
However, his minor children are not able to wholeheartedly give up on anything, and thus he cannot stipulate that they won't eat,
in return for any benefit.
There can be four types of custodians, and we mentioned them earlier.
An unpaid custodian watches over his fellow's possession and does it as a friendly service. Should anything happen to it,
such as if it stolen, lost or broke, or if it is an animal and it dies - the custodian can take an oath
that it was not his fault and he was not negligent - and be free of any liability.
A borrower is also a custodian, but his liability for mishaps
is greater: he pays in the case of every occurrence above. Only if the item broke in the course of normal use,
the borrower does not have to pay, because he borrowed it to use, not to put in storage.
A paid custodian and a renter - their liabilities are between the two previous extremes:
if an animal broke a limb, was captured or died of natural causes,
they can take an oath that they were not negligent, and they don't have to pay.
Art: Boy Eating Grapes by Joaquin Sorolla y Bastida