If somebody owes another person money for regular wages because he hired him to work, or owes him money for renting an animal from him, or owes him payment for renting kelim, utensils, he is required to pay him on time as a mitzvat aseh: that you should pay him his wages on that day. And also the lo ta'aseh: you're not allowed to keep the payment of your worker with you overnight until the morning.
Now we'll talk about when this issur (prohibition) applies and when it doesn't. When does a person violate this issur by not paying his worker on time? When the worker asks him for his money and the employer doesn't pay him during the proper time. But if the worker didn't ask for his money, then the employer doesn't violate this issur if he doesn't pay right away, because he can assume that the worker doesn't want to be paid right away. Sometimes people are okay waiting a little bit for their money, so if the worker never asked for it, he can't assume that the employer is going to give it to him, and the employer wouldn't violate the lo ta'aseh in that situation until the worker has asked.
If the employer sent the worker to a shopkeeper—in other words, if he arranged for a person who owns a store to give either food or the value of the wages to this worker—or directed him to go to a money changer, the money changer is going to pay the worker and handle the payment. The employer does not violate this prohibition if the shopkeeper or money changer doesn't pay the worker on time, or before the end of the period when he was supposed to pay him.
Now that we've talked about the proper times for these workers to be paid, we'll talk about a halacha (Jewish law) that applies during that time period. If a worker asks for his payment during the period when he's supposed to be paid, as we discussed regarding that pay period, and the employer says, “I already paid you, I already paid you,” the worker can swear that he wasn't paid and collect the money from the employer. We believe the worker over the employer because we can assume that the employer is busy. He has a whole business to run, and therefore he may have thought that he paid the worker, but he didn't actually pay him.
Once the time for the worker to be paid has ended, it's over. If the worker claims that he wasn't paid and the employer claims that he already paid him, the worker cannot swear and collect his money. Rather, here, it's the employer who swears that he paid the worker, and the employer wouldn't have to pay him. We make this assumption here because even somebody who's busy—an owner of a company who's busy—makes sure to pay his workers before that deadline because he doesn't want to violate the command of the Torah. Once that deadline has passed, we believe the employer, and not the worker.
If there are witnesses who testify before us that the worker asked the owner for money before the deadline, and the owner pushed him away and said, “Come back to me later,” then even after the deadline has passed, the worker can swear that he wasn't paid and collect the money. In this situation, we believe the worker even after the deadline because the employer wasn't concerned with paying him on time. He wasn't nervous, thinking, “I'm missing the deadline.”
If somebody is a non-Jew who lives in Eretz Yisrael (Land of Israel), is not an idol worshiper, and works at night, he is subject to the halacha that he has to be paid before sunset. But if he was hired as a day worker, he wouldn't be subject to the prohibition, “Don't leave the wages of your worker with you overnight until the morning,” and therefore he wouldn't have to be paid before the next morning.
So we see that we have two different Pesukim (verses) here. The first one deals with the night worker. The wording here implies that it doesn't apply only to a Jew, but applies to anybody as well. We infer that from the Pasuk (verse). It's a general Pasuk and it applies to everybody. But when talking about the person who is a day worker, working just during the day, the ger toshav (resident alien) wouldn't apply to that because we use the word re'echa here: your friend. That means somebody who's a member of Bnei Yisrael (Children of Israel). Therefore, for the day worker—the person who's working during the daytime—who is a ger toshav, the obligation to pay him on time wouldn't be in effect if he wasn't paid by the next morning.