As we have learned, paying a worker on time is a biblical commandment. In two places the Torah commands that a daily worker must be paid promptly –
Vayikra 19:13 lo talin pe’ulat sakhir itkhah ad boker – “do not retain the wages of a hired worker until the morning,” and
24:15 be-yomo ti-ten sekharo, ve-lo yavo alav ha-shemesh – “on that day give him his wages; the sun should not set on it.”
It appears that both situations described by the Torah are cases of a wage earner – someone who gets paid by the day or by the hour. What would the halakha be for a kablan – a contactor who gets paid when he completes the job? Would the laws of lo talin and be-yomo ti-ten sekharo apply also to a contractor who finishes the job? This question was presented to Rav Sheshet, who ruled that the same laws would apply.
The Gemara posits that the underlying question at hand is whether or not uman koneh be-shevaḥ keli – does the artisan take possession of the object through his work. If we believe that uman koneh be-shevaḥ keli, then the object becomes his when he begins working on it, and we view him as extending a loan to the true owner. When he returns the object, he is owed money – the value of the work that was done – which we view as money amount that he had lent to the owner. The laws of timely payment do not apply to loans, so they do not apply in this case. If, however, we reject the idea of uman koneh be-shevaḥ keli, then the payment that he is to receive are simply his wages, where the laws of lo talin and be-yomo ti-ten sekharo do apply.