Kiddushin 48B

אינה לשכירות אלא בסוף. ומר סבר: ישנה לשכירות מתחלה ועד סוף.

The obligation to pay a wage is incurred only at the end of the labor, when he returns the item to her. Since it is at this stage that he forgives the money due him and converts it to money for betrothal, it was never considered to be a loan. And one Sage, i.e., the Rabbis, holds: The obligation to pay a wage is incurred continuously from the beginning of the period he was hired to its end, at which point the debt is viewed as a loan that has accumulated throughout the period of hire.

ואיבעית אימא: דכולי עלמא ישנה לשכירות מתחלה ועד סוף, ומקדש במלוה ⁠– אינה מקודשת, והכא, באומן קונה בשבח כלי קמיפלגי. מר סבר: אומן קונה בשבח כלי, ומר סבר: אין אומן קונה בשבח כלי.

And if you wish, say instead that everyone agrees that the obligation to pay a wage is incurred continuously from the beginning of the period he was hired to its end. And they also agree that in the case of one who betroths a woman with a loan, she is not betrothed. And here the case is not discussing a hired worker but a contractor, who is entitled to payment only upon completion of the job, and they disagree with regard to the question of whether or not a craftsman acquires ownership rights through enhancement of the vessel. Is it viewed that the contractor has acquired the item by improving it, and he is then selling it back to the one who hired him? Or is he merely being paid for his labor? One Sage, R' Meir, holds: A craftsman acquires ownership rights through enhancement of the vessel, and since he partly owns the jewelry he can betroth a woman with it. And one Sage, i.e., the Rabbis, holds: A craftsman does not acquire ownership rights through enhancement of the vessel.