The reward that G-d gives could be viewed like payment made by the property owner to the contractor who is constructing a building for him. Payment is always due at the end of the work, as we are taught (Bava Metzia 65a, Kiddushin 48b) “Rent/payment is due only at the end [of the rental/contract period].” So only when the person has completed the job is he entitled to payment. This is reasoning of the opinion that states (T.B. Kiddushin 39b) “Payment for Mitzvoth does not exist in this world.” Since the job of doing Mitzvoth continues as long as a person is alive in this world, payment is not due to him until he reaches the next world.
Since an employer doesn’t owe payment until the task is complete, and the Torah is infinite, with no possible completion, it appears that there should be no reward due for studying greater quantities of Torah. (There is never a completion of the task, so no payment can ever be due!)
However, every element of Torah learned is, in fact, an end in and of itself. Whatever was learned is considered a complete task. Before he studied it, the person did not know this part of the Torah. Now he does. That itself is a complete objective, and for accomplishing this task reward is due to the person. But it can’t be for the actual quantity of Torah that was studied, since there is no quantity of Torah for which it can be said that he has completed the task of studying or knowing “a lot of Torah.” As much Torah as the person studies, there is so much more that he doesn’t know.
Therefore, the Tanna teaches us that if you have learned “a great amount of Torah” you are given a great amount of reward. As we said above, when man toils and struggles in Torah, he receives reward for this, since he has successfully completed the task he is assigned. One who is hired to plant seeds is paid for the time he spends planting and the number of seeds he planted, (rather than for the crops that were produced) since he has successfully completed the task he was given. The task of man is to study the Torah, not to complete it. For the study he is given reward, and the more he studies it, the more reward he receives.
There appears to be a difficulty in the language used in the Mishna. (As usual, understanding why the unexpected word was used will help us gain a deeper and more precise understanding of the intention of the Tanna. This is a fundamental method of the Maharal’s analysis of Rabbinic texts.) The Mishna states “you are GIVEN a great amount of reward.” Why did didn’t it say “you are PAID a great amount of wages?” In fact, when dealing with PAYMENT, it is always the amount the person has EARNED and is due to him. So it is not accurate to say you are PAID A LOT. You are PAID exactly what you earned. If the Tanna wants to emphasize the great quantity of reward the person will receive, it is appropriate to use the verb “GIVEN,” since the person is being paid for his effort, which is more than payment for the results that were accomplished.
Another question that needs to be considered is why the person doesn’t receive his payment immediately. The Torah mandates that a worker be paid immediately upon completion of his task. There is an explicit prohibition “Do not delay the payment of wages overnight” (Vayikra 19:13) as well as a positive command “On the day [it is due] you must pay his wages” (Devarim 24:15). The Torah makes no distinction between a poor person (who needs the wages for daily survival) and a rich person (who may have no immediate need for the money). The law about timely payment of wages differs from other timely financial commitments that a person makes which he does not fulfill. If a person promised to make a payment for a purchase or a loan, and he delayed the payment, he does not violate a specific Torah prohibition (although he is considered an “unreliable person,” which is viewed very negatively see Bava Metziah 49). The difference between paying wages and paying other financial commitments lies in the nature of a worker and his striving. A person who works is considered as being in a state of motion, moving towards a goal which he longs to attain, when he will ultimately reach a state of rest and completion. Wages and payment is the ultimate conclusion, which the person attains at the completion of the endeavor and struggle. It was for the completion of the task and it’s reward that he struggled so hard. One who does not provide this payment deprives the worker of the proper completion of the task and state of rest that he seeks, and for this reason the Torah imposes an explicit prohibition. This is very different from someone who buys a house (or any other material object) and doesn’t pay for it immediately. Since the money is not payment for work and effort, no prohibition is violated if the payment is delayed.
This distinction is creates the basis for the statement of the Tanna “Your Employer is reliable to pay you the wages of your labor.” Even though there is no immediate payment for your efforts, your Employer can be relied upon to pay your wages in the World to Come. And you should not be troubled by the fact that your wages aren’t being paid immediately (as is normally required). For your wages can be compared to a worker whose compensation is set as being a certain amount of the grain that will be harvested at the end of the season. The employer only pays the wages when the new grain has come into existence. (Until that time he is not required to pay anything.)
The work of a person in this world is of a similar nature. There are tasks for which the wages are due immediately, and there are other tasks where the wages don’t yet exist. A person might leave this world without having received the reward due to him (since that reward doesn’t really exist in this world). And he might even leave the world having received NO reward. It is for this possibility that the Tanna teaches us “the payment of reward to righteous people is done in the World to Come.” The main reward is, in fact, only in the eternal Next World, and not in this world. So a person’s work is actually being done for wages that are only available and due in the next world. It is for this reason that one should not be surprised when wicked people do not receive punishment in this world for their sins, nor do righteous people receive immediate reward. Real payment is only available in the World to Come, and it can only be given at that time.