“Be a disciple of Aharon – one who loves peace, one who pursues peace, one who loves people and who brings them closer to Torah” — Hillel (Avot 1:12).
Whenever Aharon met a sinful person as he walked along his way, he would greet him. The next day the same fellow, contemplating a sin, would say to himself: “If I do this, how will I face Aharon? I’d be so ashamed after the greeting he gave me.” In this way a Jew was prevented from sinning.
When two people had a dispute Aharon would approach each of them separately and say to him: “Look what’s doing with your friend. He’s pounding his chest, tearing his clothes and saying, ‘Woe to me for how can I look at my friend’s face; I am so ashamed because it was I who wronged him’.” Aharon would continue in this way until he had completely removed all hostility from him.
The two unsuspecting quarrelers would subsequently meet in the street, embrace each other, and resume their friendship.
Avot of Rebbi Natan 12:3