The positive commandment of giving tzedakah is explicitly mentioned in our parsha: "If there will be a needy person among you... do not harden your heart... you shall surely open your hand...".
It is known that all the parshas in the Torah have a connection with the time in which they are read. Therefore, it is understood that there is a special connection between the mitzvah of tzedakah and the month of Elul, since Parshas Re'eh is always read close to Rosh Chodesh Elul (either on Shabbos Mevarchim the month of Elul, or — as in this year's arrangement (5748) — on Rosh Chodesh Elul). This implies that in the month of Elul, one should increase in the mitzvah of tzedakah more than during the rest of the year.
We can find a source for this by examining the precise language of the Rambam in Hilchos Teshuvah regarding the Ten Days of Repentance. He writes:
"Even though the sounding of the shofar on Rosh Hashanah is a decree of the Torah, there is a hint in it, as if to say: 'Awake, you sleepers... and improve your ways...' Every person should see himself... as half meritorious... if he performs one mitzvah, he tips the scale for himself and the entire world to the side of merit and brings salvation and rescue to himself and to them... Because of this matter, the entire House of Israel has the custom to increase in tzedakah and good deeds and to engage in mitzvos from Rosh Hashanah until Yom Kippur more than during the rest of the year, and they all have the custom to rise at night during these ten days and pray in the synagogues with words of supplication and submission until the day dawns."
From the fact that the Rambam separates the custom of "increasing in tzedakah" from the general category of "good deeds and engaging in mitzvos," and furthermore, that he places it before the other matters, it is proven that although during these days there should be a strengthening in all matters of Torah and mitzvos, first and foremost, one must "increase in tzedakah."
From this, we can learn something similar regarding the month of Elul, since it is similar to the Ten Days of Repentance in several aspects: (a) Elul is the month of teshuvah, similar to the Ten Days of Repentance, (b) just as these ten days are a preparation for the "sealing" of Yom Kippur (as explained by the commentators, this is the reason for increasing in tzedakah, etc., during these days, because "the beinoni is suspended until Yom Kippur; if he repents, he is sealed for life") — so too, the entire month of Elul is a preparation for the "writing" (the beginning of judgment) of Rosh Hashanah. (c) Moreover, all forty days from Rosh Chodesh Elul until after Yom Kippur are a continuous and singular entity of days of teshuvah, as explained in the Bach: "I am my beloved's and my beloved is mine" — the acronym of Elul and the final letters add up to forty, corresponding to the forty days from Rosh Chodesh Elul until Yom Kippur, for during these forty days, teshuvah is accepted, etc., and the Beloved is close to accepting teshuvah out of love.
From this, it is understood that just as during the Ten Days of Repentance there is a special matter of "increasing in tzedakah," so too in the month of Elul, the initial strengthening in matters of Torah and mitzvos in this month should be in the matter of tzedakah, "to increase in tzedakah." It can be said that this is also hinted at in the fact that the combination of the Name of Havayah that shines in the month of Elul is derived from the final letters of "and tzedakah will be for us because."
We need to understand: What distinguishes the mitzvah of tzedakah from all other matters of Torah and mitzvos, such that the strengthening in the month of Elul (and the Ten Days of Repentance) is specifically in the matter of tzedakah?
It could be suggested that this is because giving tzedakah atones for sin, as it is written, "and your sin will be redeemed with tzedakah," and as the Alter Rebbe elaborates in Iggeres HaTeshuvah.
Based on this, we can explain the precise language "to increase in tzedakah." Seemingly, according to halacha, there is a set measure for tzedakah: a common obligation — a tenth, a fifth for the most preferred mitzvah, but not more than that, as the Rambam writes, "Anyone who distributes... should not distribute more than a fifth." However, here, since it refers to tzedakah that is for the redemption of the soul, there is "no concern for not distributing more than a fifth, as it is not considered wasteful in this case, since it is done to redeem one's soul," and this is why the Rambam specifies "to increase in tzedakah" without setting a measure for this tzedakah — because this tzedakah has no measure.
However, it seems forced to interpret it this way, since the Rambam specifies the custom "to increase" — "in tzedakah and good deeds and to engage in mitzvos," and it does not seem plausible to say that there are two different matters here: an increase in tzedakah as part of the act of teshuvah, and an increase in good deeds and mitzvos to tip the scales of judgment towards merit. It is more reasonable to say that he is only explaining the tipping of the scales of judgment towards merit. And even within the category of good deeds and engagement in mitzvos intended to tip the scales towards merit, there is an emphasis and advantage in increasing tzedakah.
This can be understood by first examining the precision of the Rambam's wording there — where he writes about the custom of increasing in prayer and supplications at night in a separate clause ("and they customarily all rise at night, etc.") — seemingly, it should have been stated in one clause, "to increase in tzedakah, etc., and to rise at night, etc."
We can explain this as follows:
In general, there are two ways in which a person receives their needs from the Holy One, blessed be He, as stated in the Gemara on the verse "Listen to Me, you stout-hearted, who are far from righteousness": "The entire world is sustained by tzedakah, and they are sustained by strength": 1) "The entire world" receives their needs from the Holy One, blessed be He, only as an act of tzedakah and kindness from G‑d, not because of their own merit, as they are not deserving of it based on their actions. 2) The righteous "are sustained by strength, by the merit they possess, and they are called far from the righteousness of the Holy One, blessed be He," because they are sustained by the merit of their good deeds.
In the service of G‑d, these two ways correspond (in general) to the distinction between prayer and the engagement in Torah and mitzvos: The matter of prayer is a request and supplication, "The poor speaks entreaties," that the Holy One, blessed be He, should have mercy on him and fulfill his desires even though he is not deserving of it, in the language of the Sages, "a free gift." However, through the engagement in Torah and mitzvos, a person receives their needs (not as tzedakah, but) according to justice, as we are promised in the Torah, "If you walk in My statutes and keep My commandments, etc., I will give your rains in their season, etc."
Based on this, when the Holy One, blessed be He, judges a person, and "weighs a person's merits and sins," it stands to reason that when He judges them favorably, it is not due to mercy and tzedakah, but according to their status.
Therefore, one might think that during the Ten Days of Repentance, the main emphasis should be on increasing mitzvos and good deeds to merit in judgment, and there is no place for requesting mercy, that it should be "in tzedakah," beyond the letter of the law.
[And although regarding prayer we find that "even though the righteous have the merit of their good deeds to rely on, they only request from the Omnipresent as a free gift" — this is appropriate only concerning prayer and request, where one does not need to demand from the Holy One, blessed be He, but only to ask from Him, in the manner of a free gift (even though they could rely on their good deeds). However, when it comes to judgment, where the Holy One, blessed be He, weighs a person's merits, etc., and judges them according to their deeds, there is no place to mix in a request for mercy and tzedakah, etc.]
And the Rambam informs us that in addition to the custom of increasing in matters of merit (tzedakah and good deeds and mitzvos), the Jewish people also customarily "rise at night... and pray... with words of supplication... until the day shines." And it can be said that this itself, that they merit in judgment according to the letter of the law, is in the category of "tzedakah" from above, because human actions (the creations) do not hold significance before Him, as it is written, "If you are righteous, what do you give Him, etc.," and furthermore, even the performance of good deeds (by a person) is through the power of the Holy One, blessed be He, as it is written, "Who has preceded Me that I should repay him, etc." Therefore, the very fact that the Holy One, blessed be He, (so to speak, lowers Himself and) judges a person and considers their good deeds as meritorious in judgment, is a kindness and tzedakah from Him, and for this, supplications are needed, etc.
Therefore, the Rambam divided these customs into two clauses, because they are two separate matters in the actions of the Jewish people to merit in judgment: the first clause is the things that the Jewish people do to tip the scales, and the second clause — prayer and supplications, because for these very things to tip the scales towards merit, they need the mercy of the Holy One, blessed be He, as mentioned above.
It can be said that this is also the reason for the change in language between the two clauses — in the first clause, "all the house of Israel have the custom," and in the second clause, "everyone has the custom" — which implies somewhat that the second matter, the custom to rise, etc., is a more straightforward practice for everyone than the first matter. According to the above, it is understood that requesting mercy is relevant to every Jew, even those who have not increased (so much) in mitzvos and good deeds (because they were unable to increase, and the like). On the other hand, even those who have increased in mitzvos and good deeds more than the entire year also have the custom to increase in requesting mercy ("words of supplication"), because they too need to know and feel that their merit in judgment is in the category of the righteousness of the Holy One, blessed be He, for which they need to request and supplicate.
With this, we can also explain why the Rambam separated "and to increase in tzedakah" from the general rule in the first clause and placed it before the other matters — because increasing in tzedakah also emphasizes that a person feels they need to merit in judgment only due to the righteousness of the Holy One, blessed be He. Therefore, they increase in tzedakah so that the Holy One, blessed be He, will also act towards them in a manner of tzedakah, measure for measure. That is to say, the feeling that everything one merits from above is in the category of tzedakah and a free gift should be expressed not only in their prayer but also in their actions, whose intention is to tip the scales of judgment for good according to the law. Even in these actions, it needs to be emphasized that this is beyond the letter of the law towards above.
Explaining the connection of "tzedakah" to the judgment of Rosh Hashanah in a deeper sense (and according to the inner dimensions of the matters):
In defining the essence of the service of Rosh Hashanah, our Sages of blessed memory said that the Holy One, blessed be He, said, "Say before Me on Rosh Hashanah Malchuyos, Zichronos, and Shofaros; Malchuyos so that you will make Me king over you, Zichronos so that your remembrance will come before Me for good, and with what? With the shofar."
Based on this, it is explained in many places that the primary service of Rosh Hashanah is crowning the Holy One, blessed be He, as King over Israel ("that you will make Me king over you"), and thereby as King over the entire world.
This does not contradict the explicit statement that Rosh Hashanah and Yom Kippur are days of judgment, because both aspects are present: from the perspective of the Holy One, blessed be He, the true content of these days is that they crown Him as King, which primarily concerns (so to speak) the Holy One, blessed be He, as expressed in the phrase "Say before Me... so that you will make Me king over you," which the Holy One, blessed be He, requests from the children of Israel, because it is something that concerns Him. From the perspective of the creations, and as the Holy One, blessed be He, so to speak, lowers Himself to sit and judge all the inhabitants of the world, these are days of judgment and justice where the merits and sins of a person are weighed.
According to this, it can be said that the need for an increase in good deeds, etc., is due to the second aspect of these days. However, from the perspective of the Holy One, blessed be He, Himself, as He is above being a king over a nation, there is no place at all for the judgment and justice of the people, which is only when He sits on His royal throne and judges the people. In order to effect this matter, that the Holy One, blessed be He, lowers Himself to be a king over a nation, it is through the complete nullification felt by the people, that even when, according to the "calculation" of merits and sins, a person is righteous and merits in judgment (and certainly has repented properly), nevertheless, they pray with supplications, and moreover, they increase in tzedakah, in order to merit the righteousness of the Holy One, blessed be He — this brings about "that you will make Me king over you."
Just as this is emphasized and in the "palace of the king" during the Ten Days of Repentance, so too is it in a small measure (in the "field") also in the service of the month of mercy and forgiveness — the month of Elul, which also contains these two aspects:
On one hand, it is the month of mercy and forgiveness to the extent that "there are those who increase in saying Selichos and supplications from the beginning of Elul onwards", and on the other hand, it pertains to meriting in judgment. As emphasized in the words of the Tur, "and whoever increases in requesting mercy, it is a merit for him," which at first glance seems contradictory, for the content of requesting mercy is that even though he has no merits, he asks that the Holy One, blessed be He, have mercy on him, which is the opposite of "it is a merit for him." However, the way to merit in these days is by feeling that one always needs to request mercy from the Holy One, blessed be He, to grant him tzedakah and a free gift.
Similarly, on the other hand, even in the increased effort in the service of repentance and good deeds [as explained many times, the hint to this is in the acronym of "Elul" where all three pillars of Torah, service, and acts of kindness are hinted at, as well as the service of repentance and the concept of redemption] — even in this itself, there must be a preface of increasing in charity, as alluded to (as mentioned above in section 1) in the combination of the Name of Havayah for the month of Elul, derived from the final letters of the verse "and it will be righteousness for us."
Through this conduct, each person merits to be inscribed and sealed in the book of the completely righteous, and even before Rosh Hashanah, they know that they will be meritorious in judgment — for a good and sweet year, with visible and revealed good.