What is the source for the requirement to forgive those who have wronged us?
In Gen.Ch.20, Abraham prays that Avimelech be forgiven for taking Sarah; this shows that we must forgive those who wrong us. Joseph forgave his brothers for selling him into slavery; see Gen.45:4-8 and 50:15-21. David instructed Solomon to punish certain people after he died (1 Kings 2:5-9), but this was because they deserved the death penalty and David had promised them that he wouldn’t personally punish them. Forgiving our fellowmen is a basic principle, stressed repeatedly in Rabbinic literature, beginning with Mishnah Yoma 8:9. But it’s hard for people to live up to the Torah’s high standards in such matters as loving our fellow-men, not being vengeful or holding grudges, and forgiving.