I have explained [a resolution to the above question] by way of a pleasant parable, [as follows]:
Reuven bears hatred against one person whose name is Shimon, and [Reuven initiates] a quarrel with him. Afterwards, one man arrives whose name is Yihudah, this Yihudah being held in the eyes of Reuven and in the eyes of everyone, to be a man of truth, [comes to Reuven] and recounts [to him,] saying how the man Shimon, “against whom you bear hatred, and you told me that he wasn’t a decent man [and is] a despicable man, [well], a number of days after [you related the above information about Shimon], I saw that he was [present] by one Torah leader of the generation, who is widely known to be a gaon and [to be] a righteous [individual, as well as] a great scholar, with no one [to] compare [to his Torah scholarship. This great Torah leader] greatly honored [Shimon] and, in a number of matters, displayed to [Shimon] signs of his affinity [toward him]. My brother, you have been greatly mistaken [in your conclusions as to the character of Shimon, as well as your disparaging comments about him]!” Once Reuven heard this matter [relayed to him by Yihudah], he was astounded about this matter [vis-à-vis Shimon], and responded [to Yihudah]: “You have brought doubt into my heart, for perhaps the truth is with Reb Shimon [who is] mentioned above, and only due to [the fact] that all [the actions] of a person [are] upright in his eyes, it had appeared to me that the law accords with me. Or, perhaps, in truth the law [does lie] with me, just that Shimon, [who is] mentioned above, is a man of deceit, and through his words of flattery, he caused the Gadol HaDor, who is mentioned above, to err [in his high regard of Shimon], to the point that it appeared [to him] that Shimon is a respectable man. Nevertheless, I shall not continue to speak [negatively] against [Shimon] due to the doubt that you have brought into my heart [vis-à-vis his guilt]”.
Afterwards, [once] a number of days [had passed], this man Yihudah came to [Reuven], he being held in [Reuven’s] eyes to be a man of truth. [Yihudah] then relates to [Reuven], saying [as follows]: “[I wish to relate to you] about how I have seen a more wondrous matter [than that which I related to you previously], that being that the man, [Shimon], about whom you [conveyed] to me that you still have a doubt about [his status as a respectable person, thinking that he may be] a man of deceit, and a man who is indecent, [well], I have seen that he was invited afterwards [to be present] by the [Torah] scholars of the earlier generations, and they also [demonstrated] great deference [toward Shimon], and they displayed their signs of love [for him] before all those present. Concerning the one Gadol HaDor, [about whom] I initially related to you [of his great admiration of Shimon], you responded to me that [Shimon] caused [this Torah leader] to err, [leading him to wrongly believe that Shimon is a respectable person]. However, with respect to these people, [the sages of the earlier generation, the above argument of yours] is not pertinent!” Once Reuven heard [of] this matter [relayed to him by Yihudah], he immediately responded, [as follows]: “The [truth] is with [what] you [have said], for my Yetzer [HaRa] deceived me in the essence of the matter.”
The [individual] Yihudah, [who we have] mentioned above, [continued by relating to Reuven], and related another [astonishing] incident [involving Shimon, as follows]: “Indeed, I know concerning this Shimon, that he was invited [to be present] by the early Sages of Israel, Rabbi Meir, Rabbi Yihudah, and Rabbi [Yihudah HaNasi, the] composer [of] the Mishnayos, as well as their contemporaries, who were [worthy to be] frequented by Eliyahu [HaNavi], as is known. [These outstanding scholars, in addition to the previously mentioned Torah leaders], also glorified and praised [Shimon. In addition], Eliyahu HaNavi related before the aforementioned Tannayim, [concerning] how [the] Rabbi Shimon, [whom we have] mentioned earlier, is spoken about Above, [in Heaven], as well as [that] he heard from the Mouth of The Holy One, Blessed is He, that He loves [this] Rabbi Shimon.”
Once Reuven heard [of] this matter, he recoiled and fell on his face [in regret], and he said: “Woe to me, regarding [my having] initially thought that I am righteous and he is the evildoer, for according to that which I now [recognize, what I initially suspected] was not truly the case. [I now recognize that I am in the wrong], for The Holy One, Blessed is He, He being The Root of everything, [Who] knows that which is done in darkness and in open, Whose actions are perfect and all His ways are justice, when He loves a person, He definitely does not love him for no reason! With respect to the matter involving me and this honorable Rabbi Shimon, who is mentioned earlier, I contemplate a number of explanations [that would exonerate him of wrongdoing they being as follows]: A) The law goes with [Shimon] in the essence of the matter. Only as the matter [involves] me, and I was not [sufficiently] familiar with [this individual], Shimon, I imagined that the truth and the righteousness accorded with me, this being the matter that was the closest to me, [thus leading me to incorrectly conclude that Shimon was not a decent person. B)] Or, perhaps this matter [in which Shimon wronged me] occurred unintentionally, he himself [having] greatly regretted [having wronged me]. It is also possible that he intends in his mind to appease me regarding this [matter]. Or, [perhaps] there is another matter [that would demonstrate Shimon’s] innocence, of which I am unaware. In the meanwhile, I [am in] possession [of] a great sin concerning that which I have spoken about an individual, [about] whom The Holy One, Blessed is He, said concerning him that he [among those that] He loves. Apparently, the root of his soul, Above, [in Heaven], is exceedingly holy and awesome. I [greatly sinned by] having declared and publicized [Shimon] to be an individual who is indecent, a despicable person, [as well as] a man of deceit. From this moment, I very greatly regret [having arrived at a negative conclusion concerning Shimon and then having derided him]. [Furthermore], now [that I am aware] that The Holy One, Blessed is He, is [Shimon’s] friend I do not possess any hatred against him.”
[The above parable addresses the] intended [meaning] of the pasuk, with [reference to the phrase] “Do not take revenge and do not bear a grudge [against] the people of your nation, and you shall love your fellow [as you love] yourself…” (Vayikra: 19; 18) Perhaps you will say: In what manner will I be able to conduct myself, so that I do not have any complaint against [an individual who has wronged me], and even [come to] love him? The answer to this [question is found in] the [concluding phrase of the] pasuk, [where it states], “I am HaShem”, [which] means [as follows]: “I am HaShem Who have loved [this person]”, as is written in [sefer] Malachi, “I have loved you, says HaShem…” (Malachi: 1; 2), [and in sefer Divarim, the pasuk states], “You are children to HaShem, your G-d…” (Divarim: 14; 1), [Since HaShem loves this person], you are also able to love him. In truth, this matter [concerning how a Jew can react negatively toward his fellow], is obvious, for the person, since he only views [his fellow, below, [in this world], he being enclothed in material of physicality, [his fellow] is [therefore] not so important in his eyes. Specifically, if in a given matter [his fellow] is at odds with him, he considers [the other person to be] inconsequential in his mind. The same is not true of The Holy One, Blessed is He, for He actually knows of the root of the holiness of the soul of Israel, it being exceedingly great and awesome, as is written in the Holy Zohar in a number of places, [where we learn] that the root of the holiness of the soul of Israel is elevated, [existing] in an exceedingly awesome place. Therefore, the importance and love [that HaShem has toward the Jewish People], is also exceedingly [great].”]
 “Gaon” refers to an individual who is an exceptional Torah scholar, and is considered a “gaon” – “genius” in Torah matters.
 “Gadol HaDor” refers to the Torah leader (or one of the Torah leaders) of the generation. “Gadol HaDor” literally means “great one of the generation”.
 "Yetzer HaRa" is one's evil inclination and regularly attempts to encourage the individual to sin.
 “Tannayim” refers to those rabbis who are recorded in the Mishna.
 This teaching can be found in the Zohar in Volume 3: 252b, see [also] in Volume 1: 13a.