Grudges

We all have reasons to hold grudges. People wrong us. Situations hurt us. Even God does not always do what we think He should do, so we get angry. We hold offenses against those who have wronged us, and often against God who we think should have done things differently. A grudge is nothing more than a refusal to forgive. So, since this tendency is inherent in all of us and seemingly unavoidable, what does the Bible say about it?