The Torah commands an employer: "On the same day you shall pay his salary, and the sun shall not set upon it, for he is a poor man, and to it he lifts up his soul" (Devarim 24:14). What does the Torah mean by "to it he lifts up his soul"?
The gemara (Bava Metzia 112a) says that a person takes his salary so seriously that he would endanger his life in order to do the job that earns him his money. That is reason to make sure to pay on time, since if the employee takes his salary so seriously, so should the employer. But let’s put things into perspective. The employee is interested in his salary, which is after all, just money. Should one risk his life for money? Should the fact that one is waiting for money make the world stand still for him? If yes, why is there no parallel mitzva regarding one who owes money for any reason (loan, damages, etc.)?
Before trying to answer these questions, let us see another explanation by the gemara (ibid. 111b) for this pasuk. The gemara says that a person who works gives of himself by becoming an employee. Rashi explains that he "enslaves" himself by taking the responsibility of being a worker. This can be seen practically as agreeing to do hard work (see Yaakov’s description of a proper work ethic). However, the gemara implies that even when the work is not so hard, the same phenomenon is assumed to exist.
Hashem decreed upon Adam and his descendants that they would have to work hard in order to ensure their sustenance. Those who are self employed, live up to this necessity as they work before Hashem alone. However, others become slaves of sorts to other human beings. (For this reason, the halacha is that one must be able to back out of his work obligation or he would violate the prohibition of making himself a slave.) Hashem did not want to create a situation where some people were, to a certain extent, being enslaved while others were enslaving them. Therefore, the Torah decreed that whenever an employee obligated himself, whether by endangering himself or simply by agreeing to commit his time and energy to another, he would not be alone. His employer would also be subjugated to the very strict task of paying within a short amount of time. This is not just a matter of paying debts. Rather, the laws of payment "level out the playing field" so that both employer and employee feel a real obligation and therefore neither feels all powerful or powerless.
The Torah sees the worker as one with great responsibilities, but the Torah also sees him as an equal to his employer. The worker’s needs must also be addressed and his status must be safeguarded.