By Rabbi Aharon Seleh:
The Chida quotes Rav Moshe Kordovoro as follows: The best type of Teshuva a person can do is to bear an insult and forgive that person. This will atone for many of his sins. The Gemara says in Rosh Hashanah: one who forgives another who has wronged him, will be forgiven from Hashem for his sins. The Chida says this is the best medication of all. You could go and enjoy life with out having to suffer for sins. This is not an excuse to avoid Teshuva. But many times Teshuva is not complete and peoples’ sins linger and people will have to suffer. By continuously forgiving others, you’re continuously being forgiven.
Look at it this way. When Hashem sees a person’s sins have racked up, He might choose to send you someone to embarrass you or insult you, to give you the opportunity to have your sins forgiven! Hashem is looking for opportunities to drop your sins. People who don’t forgive are only hurting themselves. Chacham Eliyahu Netaneli said if one realized how much good comes to them when they are embarrassed in front of others, would run in the street looking for others to embarrass them! Of course it’s a terrible sin to embarrass another. But for the person on the receiving end, it’s a golden opportunity!