[Due to the trait of complaining, the person] is also very likely to come to [involve himself in the] sin of baseless hatred, concerning which there is an explicit prohibition in The Torah, [as follows]: “You shall not hate your brother in your heart…” (Vayikra: 19; 17) [The sin of baseless hatred has such a great destructive power, for] The Second [Beis] HaMikdash was destroyed due to this [sin], as [the Sages] have [taught us] in [maseches] “Yoma”(9b). [Furthermore, the punishment for baseless hatred has been taught] in [maseches] “Shabbos” (32b), [as follows]: “Due to the sin of baseless hatred, great discord [develops] in the house [of such a] person, and his wife has miscarriages, and his sons and daughters die when they are children…”
[In addition to the aforementioned punishments that a person may experience as a result of his baseless hatred], he also transgresses that which The Torah said, [as follows]: “…you shall judge your fellow in righteousness” (Vayikra: 19; 15), and our Sages of Blessed Memory have explained [in maseches “Shavuos” (30a)], that the intended [meaning of the pasuk is that one is obligated] to judge his fellow meritoriously. It is [similarly taught] in “Sefer Chareidim”, that one who judges his fellow negatively, is a vehicle for the impure k’lipah that is called “חוֹבה” – “Chovah” – “guilt”.
As a result of this sin [of baseless hatred], the individual is also very likely to suspect upright people [of wrongdoing. Concerning one who suspects upright people of wrongdoing], our Sages of Blessed Memory have said [in maseches “Shabbos” (97a), as follows]: “One who suspects upright individuals [of wrongdoing], is stricken in his body.”
[The person who involves himself in baseless hatred is] also likely to come to thereby [transgress] the prohibitions of Ona’as Divarim, as well as cause others embarrassment, and will also come to [involve himself in the] sin of strife, its punishment being exceedingly harsh, as mentioned earlier, in the fifiteenth chapter of volume 1.
 The entire pasuk states that “You shall not take revenge and shall not bear a grudge against the people of your nation, and you shall love your fellow as [you love] yourself, I am HaShem.” (Vayikra: 19; 18)
It is evident from the pasuk that if one does take revenge or bear a grudge against a fellow Jew, they by definition do not love that person as they love themselves.
 The pasuk states, “You shall not hate your brother in your heart, you shall surely rebuke your fellow and not bear a sin on his account.” (Vayikra: 19; 17) (Translation based on Onkelos) This pasuk teaches us that a person should rebuke his fellow in the proper manner, rather than coming to embarrass him publicly. (Arachin, 16b) According to the RaMBa”N, rather than bearing hatred against the other person who wronged you, rebuke him and ask him why he acted against you.
 The gemara in maseches Yoma teaches that The Second Beis HaMikdash was destroyed on account of the sin of baseless hatred. Since, as the gemara notes, the First Beis HaMikdash was destroyed on account of the three cardinal sins of murder, sexual immorality, and idolatry, the gemara points out that the sin of sinas chinam – baseless hatred – is equivalent to the aforementioned three sins.
 This is a Baraisa quoted in the name of Rabbi Nichemiah.
 This teaching is found in Chapter 66, sif 39, in the new printing of “Sefer Chareidim”.
 “K’lipah” means “shell” or “husk” and refers to the spiritual barrier that separates the person from HaShem. Though k’lipos may benefit the person by increasing their free-choice, it is viewed as negative, as it serves as a separation between the individual and HaShem, potentially leading to negative spiritual consequences for the person.
 This section from maseches “Shabbos” (97a), which discusses that the body of one who suspects those who are upright of wrongdoing, is stricken. The gemara states as follows:
“Reish Lakish said: ‘One who suspects upright individuals [of wrongdoing] is stricken in his body, as it is written [concerning the incident where Moshe suspected The B’nei Yisrael of wrongdoing], “…and they will not believe me…” (Shmos: 4; 1), [though] it is revealed before The Holy One, Blessed is He, that [The People of] Israel do believe. [The Holy One, Blessed is He], said [to Moshe]: ‘They are believers the sons of believers, and you will eventually not believe.’ [The People of Israel] are believers, as it is written, “And The Nation believed…” (Shmos: 4; 31) They are the sons of believers, [as it says concerning Avraham], “And he believed in HaShem…” (B’reshis: 15; 6) ‘You, [Moshe], will eventually not believe’, as it says, “…since you did not believe in Me…” (Bamidbar: 20; 12) From where do we know that Moshe was stricken? As it is written, “And HaShem said to him again, please bring your hand into your cloak, [and he brought his hand into his cloak, and he took it out of his cloak, and behold his hand was afflicted with tzara’as resembling [the color of] snow.]” (Shmos: 4; 6)”
Of course, Moshe’s level of emunah (belief) in HaShem was on a very high level. Perhaps Moshe’s lack of emunah, as befitting someone on his level, is one of the reasons why HaShem did not permit Moshe to enter Eretz Yisrael. In fact, the pasuk in which HaShem tells Moshe that he will not enter Eretz Yisrael, states as follows:
“And HaShem said to Moshe and to Aharon, ‘Because you did not believe – have emunah – in Me, to sanctify Me before the eyes of The B’nei Yisrael, therefore, you shall not bring this congregation into The Land that I have given to them.’” (Bamidbar: 20; 12)
 “Ona’as Divarim” are “hurtful words” and refer to words which are spoken that cause people to feel hurt.
 The in-depth discussion of the destructiveness of strife is found in the fifteenth chapter of “Sha’ar HaZechirah”, Kislev 1 – Kislev 4.