Parshas Re'ei discusses an ir ha'nidachas - a situation where an entire city of people is found guilty of worshipping avodah zara. The punishment is as extreme as the transgression: The city is to be wiped out, all its contents must be burnt, and the city may never be rebuilt. The Torah concludes with an assurance, "And nothing from the banned property shall remain in your hands so that Hashem with turn back from His wrath, and He will give you mercy and He will be merciful to you" (Devarim 13:18).
The Gemara (Shabbos 151b) expounds on this pasuk. "Rebbi Gamliel the son of Rebbe says, 'And He will give you mercy and He will be merciful to you: Whoever shows mercy to people, Heaven will act with mercy toward him, and whoever is not merciful toward others, will not be shown mercy by Heaven.'" Rav Wolbe (Daas Shlomo) comments that while the first half of Chazal's declaration is logical, the second half is more difficult to understand. We can understand why one who does not have many merits can succeed in garnering heavenly mercy, since he acts with mercy toward other people and thus Hashem will deal with him mercifully. However, how are we to understand that one who learns Torah, acts honestly and possesses an abundance of other good middos, will nevertheless not be a recipient of heavenly mercy simply because he is not merciful to others?
Chazal are teaching us that if one does not act mercifully to other people it is impossible for him to receive heavenly mercy. A person's middos are vessels through which he is able to acquire heavenly bounty. Exactly proportional to the utensil prepared can one obtain heavenly bounty, and therefore, one who has not created a "receptacle" to store mercy cannot be a beneficiary of heavenly mercy.
In a similar vein, the Gemara (Rosh Hahasana 17a) tells us. "Said Rava, 'Anyone who is forgiving to another will be forgiven for all his sins as the pasuk says, 'He bears iniquity and forgives sins.' To whom does He bear iniquity? To one who forgives sins.'" One who is not forgiving simply lacks the tools needed to open the conduits of forgiveness. This concept is illustrated by a story related in the Gemara (Taanis 25b). One year there was a famine and Rebbi Eliezer, acting as chazzan, recited the twenty four brachos instituted when praying for rain but his prayers were not answered. Then Rebbi Akiva stood before the amud, recited two petitions and his prayers were answered immediately. Understandably, this caused people to question the greatness of Rebbi Eliezer. A bas kol was heard from Heaven: "It is not because one is greater than the other, rather one acts forgivingly while the other does not."
Rebbi Eliezer was a disciple of Bais Shammai and was of the opinion that one cannot just forgive and forget when it comes to an infraction to a talmid chochom because it undermines kavod Hatorah. He was not wrong in his opinion, but the reality was that he did not have the tools needed to access rain when Heaven had declared that the generation was undeserving. Only someone who practiced overlooking iniquity was able to influence Hashem to overlook the generation's shortcomings and provide rain.
This concept applies to all of a person's middos. Truth be told, most middos find expression between man and his fellow man. The manner in which we act toward others is the way Hashem acts with us. It's both frightening and exhilarating. How can a miser or an irritable person approach Rosh Hashana? On the other hand, there is nothing more invigorating than knowing that acting kindly, being merciful and forgiving others can rid oneself of mounds of aveiros! Elul is the time to take this knowledge and put it into practice!