A. Paying workers fully and promptly is a high priority in Jewish tradition. A number of Torah verses warn us about this. Here is a verse from the book of Leviticus (19:13, all translations from Living Torah):
Do not [unjustly] withhold that which is due your neighbor. Do not let a worker's wages remain with you overnight until morning.
Here is a passage from the book of Deuteronomy (24:14-15):
Do not withhold the wages due to your poor or destitute hired hand, whether he is one of your brethren or a proselyte living in a settlement in your land. You must give him his wage on the day it is due, and not let the sun set with him waiting for it. Since he is a poor man, and his life depends on it, do not let him call out to God, causing you to have a sin.
But of course these passages cannot tell us when in fact the worker is due his wages in the first place. In Jewish law, there are three distinct ways a worker's just recompense can be calculated.
The easiest case is where there is an explicit wage bargain. The employer and worker agree exactly on the demands of the job and the wage. This case is the most widespread case and the least likely to involve disputes or misunderstandings.
A closely related case is where there was no wage bargain but where there is a well-known and widespread custom. In this case, the mishna tells us, "Everything is according to the local custom". (1) The court will rule exactly as if there was an explicit contract stipulating the working conditions and pay that are customary.
In the above cases, payment is due because of the agreement or contract between the sides. In the first case the agreement is comprehensive; in the second case it is rather thin, consisting only of the agreement to hire and the agreement to work.
But there can also be an obligation to pay which doesn't stem from agreement at all. The benefit provided by the worker's actions can itself obligate payment.
One who enters his neighbor's field and plants without permission: Rav said, an assessment is made and he has the lower hand [between normal planter's wages and the increase in the assessed the value of the field]. Shmuel said, we assess how much a person would normally pay to plant such a field. Rav Pappa said: There is no disagreement. This [ruling – where the wages must in any case be paid] refers to a field which is designated for planting; this [ruling – where the worker has the lower hand] refers to a field which is not designated for planting. (2)
Even when there is no agreement at all, when there is a benefit provided the beneficiary is required to pay some reasonable approximation of the value of the benefit. (In the common law system, this corresponds roughly to the doctrine of "unjust enrichment".)
Even if you never offered to pay your workers, they would have a justified expectation of getting paid the going wage for the kind of work that they are doing. Given that the benefit provided is itself a source of obligation, even a simple disclaimer ("I'm not offering any payment") would probably not be enough. That would be enough to negate any wage agreement, but not to negate any benefit. Obviously any benefit can be waived, but a rather detailed waiver would be called for in this case.
Furthermore, in the light of the underlying law it would seem that the arrangement you describe is not fair. Your criterion for payment is totally subjective – whether you want to keep the person on; it is not directly dependent on whether the person does a good job or not.
This column is not a source of information on secular law, but to the best of my knowledge the secular law would require payment in such a situation.
SOURCES: (1) Babylonian Talmud Bava Metzia 83a (2) Babylonian Talmud Bava Metzia 101a.