Talmud for Pirkei Avot 1:12
הִלֵּל וְשַׁמַּאי קִבְּלוּ מֵהֶם. הִלֵּל אוֹמֵר, הֱוֵי מִתַּלְמִידָיו שֶׁל אַהֲרֹן, אוֹהֵב שָׁלוֹם וְרוֹדֵף שָׁלוֹם, אוֹהֵב אֶת הַבְּרִיּוֹת וּמְקָרְבָן לַתּוֹרָה:
Hillel and Shammai received it from them. Hillel says: Be of the disciples of Aaron, loving peace and pursuing peace, loving men and drawing them close to Torah. [They explained in Avoth d' R. Nathan how Aaron loved peace. When he saw two men quarreling, he would go to each one without the knowledge of the other and say to him: "Look at your friend. See how he regrets what he has done and how he smites himself for having sinned against you. He asked me to come to you and beg you to forgive him." Afterwards, when they met, they would kiss each other. And how would he draw men close to Torah? When he knew a man to have transgressed, he would befriend him and look kindly upon him — whereupon the other would think, in shame: "If that tzaddik knew of my evil deeds, how he would distance himself from me!" As a result, he would repent. This is the testimony of the prophet (Malachi 2:6): "In peace and justness did he (Aaron) walk with Me, and many did he turn from sin."]
Avot D'Rabbi Natan
Avot D'Rabbi Natan
When a person does not give part of what he earns to his fellows in this world, then he will not be given anything in the World to Come, as it says (Ecclesiastes 4:1), “Look at the tears of the oppressed, and they have no comforter. Power is in the hand of their oppressors, and they have no comforter.” Why does it say “they have no comforter” twice? This refers to people who eat and drink in this world, and their sons and daughters are successful, but in the World to Come they have [nothing and they have no] comforter. For if a person has something stolen from him in this world, or if someone he knows dies, then his children, siblings, and other relatives come and comfort him. Could it be that the same is true in the World to Come? That is why the verse then says (Ecclesiastes 4:8), “He has neither son nor brother.”
So, too, with someone whose sexual transgression produces a mamzer [a child born of certain forbidden sexual relations]. They say to him: Empty one! You have ruined yourself and you have ruined him as well! [For this mamzer would have wanted to study Torah with the rest of the students] who sit and study in Jerusalem. But this mamzer would go with them only up to Ashdod, and then would stop there and say: Woe is me! If I were not a mamzer, I would have gone to sit and study among the students whom I have been studying with until now. But because I am a mamzer, I cannot sit and study among these students. For a mamzer cannot enter Jerusalem at all, as it says (Zechariah 9:6), “The mamzer will stay in Ashdod, (and I will cut off the pride of the Philistines.”