The Rambam (a”h) writes in Sefer Hilchot Teshuva that a person earns atonement on Yom Kippur only for sins committed against Hashem, such as eating forbidden foods or engaging in illicit relationships. Sins committed against one’s fellow man, however, such as stealing, causing damage to somebody’s body or property, or even verbally insulting another, cannot be atoned through Yom Kippur alone. The sinner must also make whatever restitution payments are required by Halachah and ask the victim for forgiveness. Only by receiving the victim’s forgiveness can the sinner earn atonement for his wrongdoing.
The Rambam adds, that if the victim refuses to grant forgiveness, then the sinner should assemble three friends and approach the victim again, in an effort to convince him to forgive him. If after three SINCERE requests the victim still refuses to forgive him, then it is he – rather than the sinner – who is deemed the sinner.
Then the Rambam emphasizes the importance of responding favorably and forgivingly to those who have caused them harm and now seek reconciliation. Regardless of the crime, one should accept the apology and forgive unhesitatingly. The Rambam states that Jews are characteristically slow to anger and quick to forgive, whereas the Pagans would customarily grow angry at the slightest provocation and refuse to grant forgiveness. We are obligated to follow the Jewish tradition to graciously forgive those who seek reconciliation after having committed a wrongful act.
If a person committed an offense against a fellow Jew and the victim passes away before the sinner asks for forgiveness, then he should assemble ten men at the victim’s kever and confess his sin. If the sinner owes some form of compensation payment to the victim, he must pay the sum to the victim’s inheritors. If he is not aware of any inheritors, then he should pay the sum to the local Bet Din and confess his sin in the court’s presence.