We have learned in the Mishnah that “One must calculate the reward of a Mitzvah!”, and this is a great rule in all of Judaism, as we know that a person will work for one day in order to gain a certain amount of money, and for a greater amount of money he will be willing to work for a full week. For a tremendous amount of money he will be willing to work for a full year or even for many years with all of the effort and difficulties in the world, he will climb mountains and descend into valleys in the way of the merchants who travel from place to place who eat the sad bread. A person will not worry about all of the hard work and effort that he puts in, because he will calculate the profits that he will get through this. Sometimes even after all of the work and effort he will lose and not gain, and he will then turn around and work at other things to see maybe he can make some money. Even if he does gain a huge amount of money, it is all emptiness and waste of breath and what gain does a person have in all of his work even if he were to be a tremendously rich person as when he dies he will be unable to take it all with him as he will only be able to take with him the good deeds and commandments that he has fulfilled which he has sent up before him.
If you will ask any Jewish man how much Torah and good deeds are worth, he will answer and say that all of the gold and silver in the world cannot give a value to them, and all of the objects in the world are incomparable to them. This is true and established that anyone who does even the smallest good deed, be it in thought, speech or action, will definitely and without the shadow of any doubt gain more than one who has found a vast treasure. On the other hand, one who commits one sin, whether he transgresses a positive commandment or a negative commandment will lose a huge amount, more than someone who loses a vast fortune. All of this truth is as clear as the sun, and every member of Klal Yisrael believes in this. It follows that someone who has transgressed a positive commandment or committed a sin deliberately is comparable to someone who takes a purse full of money and throws it into the sea or to someone who commits suicide. Chazal already said that “A person will not sin unless a mad spirit enters him!”, as there is no madness greater than this.
Thoughts like these are like a ladder which brings a person upwards all the time, as when one starts doing something for the wrong reason one ends up doing it for the right reason, and he should understand in his heart that ideally one should serve Hashem without expecting a reward and do so only in order to give pleasure to Hashem as there is actually no reward which can compare to the fact that a great King who is elevated and lofty, the King of the kings of kings, wants the service of a human being who is comparable only to emptiness, and He wants us to serve Him and that our actions should be accepted willingly and be a pleasure before the Throne of His Glory. If all the reward that we would receive would be this, it would already be more than we deserve. We see this in the words of Chazal that “One hour of Torah and good deeds in this world is better than all of the life in the next world!”.