Bear with one another and forgive any complaint you may have against someone else. Forgive as the Lord forgave you. — Colossians 3:13

Paul ties forgiving others directly to Christ's forgiveness of you. Not "forgive so you'll be forgiven," but "forgive because you've been forgiven." The servant forgiven ten thousand talents couldn't forgive a hundred denarii, and that exposed an unforgiving heart. You've been forgiven an immeasurable debt at the cross. Let the small debts go. The measure you use will be measured back.