[The following is quoted from the] Midrash Rabbah, Parshas Korach (Bamidbar Rabbah: 18; 4): “Rabbi Berechiah said, ‘So harsh is strife, for the Heavenly Court does not punish [for sins, unless one is] twenty years old and over, and the Earthly court [punishes for sins committed] from thirteen years and up, [however], in the quarrel of Korach, babies [that were] one day old were swallowed into the lower levels of gehinnom, as it says, “…and their wives, and their children, and their babies.” (Bamidbar: 16; 27), “…and they and all that belongs to them descended alive into sh’ole…” (Bamidbar: 16; 33)
Our Rabbis taught (Bamidbar Rabbah: 18; 12): “Four [types of people] are called evildoers: One who extends his hand against his fellow to strike him, even though he did not [actually get as far as] hitting him, as its says…, and one who borrows and does not repay…, and one who has a brazen countenance, and is not embarrassed before one who is greater than him, as it says…, and one who is habitually involved in strife, as it says, “…Remove yourselves from upon the tents of these evil people…”(Bamidbar: 16; 26)
[Based on the above teaching], once a person knows that he caused the quarrel, [he] should be greatly ashamed of himself. [The person who initiated the quarrel should be greatly ashamed of his actions], for if his fellow would refer to him as “evil”, even privately, [thereby] causing no shame to [come to] him as a result of this [insult], the individual labeled as “evil” will, nevertheless, take it out against [the perpetrator] because of this [reference to him as “evil”]. (Bava Mitzia, 71a) How much more so [is it fitting for the individual to be ashamed of himself] as he caused his name to be called “evil” by [instigating the quarrel]. So much of the shame and disgrace will overtake him Above, [in Heaven], after [he passes away], once this “good” name is publicized among the Heavenly retinue, before many thousands of myriads of holy camps, concerning which has been written in the holy books. [The holy books record] that all of the matters of a person are announced and publicized Above, [in Heaven], before everyone, [this shame that the person suffers in Heaven is aside from the great punishment that befalls him for the quarrels in which he was involved]. This [aforementioned teaching, where we learn that one can perform sins that label him as evil], is the intended teaching of our Sages of Blessed Memory in [Pirkei] Avos, “…and do not be an evildoer before yourself.” (Pirkei Avos: 2; 13)
 The RaMBa”M – Rabbi Moshe ben Maimon (1135 – 1204) was a great Torah leader of the twelfth century and was a prolific writer and commentator on the Torah.
 “Sh’ole” refers to hell.
 “Our Rabbis taught: “Four [types of people] are called evildoers:
1) One who extends his hand against his fellow [in order] to strike him, even though he did not [actually get as far as] hitting him, as its says, “…and he said to the evildoer, ‘Why do you strike your fellow?’” (Shmos: 2; 13) [The pasuk] does not state “you struck”, rather, [it states], “you strike”, [the person not actually having succeeded in hitting his fellow].
2) One who borrows and does not repay, as it says, “An evildoer borrows and does not repay and the righteous [person] is compassionate and giving.” (Tehillim: 37; 21)
3) One who is brazen and is not embarrassed before one who is greater than him, as it says, “An evildoer will [show his] brazenness on his face [at the time of his anger], and the straight [person] will understand his path [even when angry].” (Mishlei: 21; 29)
4) One who is habitually involved in strife, as it says, “…Remove yourselves from upon the tents of these evil people…”” (Bamidbar: 16; 26)
Note: The bracketed words in the above quoted pasuk from Mishlei, reflect the explanation of Mitzudas David.
 The translation “will take it out against [the perpetrator]” is a translation of "יורד עמו לחייו". This statement is found in masechtos “Kisuvos” (50a), “Kiddushin” (28a), “Bava Mitzia” (71a), and “Yoma” (75a). RaSh”I, in maseches “Bava Mitzia”, explains that "יורד עמו לחייו" means that “[the person] is accustomed to quarrel with him as if he had hit him and as if he had come to kill him”.
 The gemara states as follows:
“We learn in a Baraisa, Rabbi Yosi said, come and [take note of] the blindness of those who lends [to a Jew] with usury: A person calls his fellow an “evildoer”, [and the one referred to as “evildoer] takes it out against [the perpetrator. However, this individual that lends to a Jew with usury] brings witnesses, the scribe, a quill, and ink. [The usurer then proceeds to] write and sign [the loan document. By writing and signing the loan document, these individuals are effectively writing the equivalent of the following]: ‘This individual [who signed the document] denies [the existence of] The G-d of Israel.” (Bava Mitzia, 71a)
The Jew who charges another Jew interest is considered to deny the existence of The G-d of Israel, for he charges usury in spite of the following Torah prohibition against charging another Jew interest:
“If you lend money to My nation, to the poor person who is with you, you shall not [act] as a creditor [would act] to him, you shall not place interest upon [his loan].” (Shmos: 22; 24)
At times, Jews make use of a “heter iska” which is a business contract between the lender and the borrower, thus avoiding the issue of interest. If one is interested in a “heter iska”, they should first contact an Orthodox rabbi familiar with such a contract, in order to find out if a “heter iska” could apply to the given situation, as well as how to go through with the “heter iska”.
 See Koheles (12; 13) in the Targum Onkelos. Also see in sefer “Ma’alos HaMiddos”, pg. 327, in the note.
Onkelos writes as follows:
“[Concerning] the end of the matter that is performed privately in [this] world, in the future it will all be publicized and heard [by] all people. [In light of the above, it is recommended that you] fear [the Presence of] HaShem, and guard his commandments, [so] that you don’t sin in private. If you sin, be careful to repent, for this is [the] fitting [behavior] of all people.”
 The Kihati brings the following explanations on the conclusion of this mishna in Pirkei Avos (2; 13), concerning the teaching, “do not be an evildoer before yourself”:
“Do not be an evildoer even in your own eyes, for you shouldn’t do something that today or tomorrow will make yourself evil. [Thereupon you might say], ‘Why have I made this evildoer?’”
“There are those who explain [the above teaching as follows]: ‘Do not be an evildoer in this matter that you separate from the community, and [thereby] stand by yourself, rather, you should be attuned to others sensitivities.’”
The RaMBa”M explains the teaching from Pirkei Avos, as follows: “Do not consider yourself an evildoer, for as a result of such [thinking], you will leave [your current lifestyle], to completely [adopt] an evil lifestyle.”