Prof. Matt Skinner, in a podcast for the lectionary for Feb. 16 on Working Preacher.com, talked about considering the larger good of the people around you when responding to the Sermon on the Mount, especially "be reconciled to your brother or sister." (Matt. 5: 24). Where may more be found on this new emphasis: "How are you going to live? Who are you as a person under the law in the light of your relationship to other persons?" This in contrast to an emphasis on only legal righteousness for the individual when considering the commandments. Where may more be found on this new emphasis (on the society around you and not just the individual's correctness)? Any particular commentaries or larger treatments?
This question takes us into an enormous, rich topic. Here are some relatively recent books that have helped me think about the topic. Maybe they aren't necessarily the best introductions to the topic, but all of them are compellingly written and informative. And, like I said, they've been helpful to me:
William P. Brown, editor, Character and Scripture: Moral Formation, Community, and Biblical Interpretation (Eerdmans, 2002).
Paul D. Hanson, The People Called: The Growth of Community in the Bible (Harper & Row, 1986).
William Loader, Jesus' Attitude towards the Law (Eerdmans, 1997, 2002)
Patrick D. Miller, The Ten Commandments (Westminster John Knox, 2009).
Sorry to list only books authored or edited by white men. These are the first things that came to my mind.
I'd look at the material on forgiveness and reconciliation.
Henderson, No Enemy to conquer (lots of great examples)
McCullough, Beyond Revenge (somewhat social science orientation, but useful
Lederach, The Journey Toward Reconciliation (I would start here)
Also: feminist Christians writing on relationality and care.
There certainly is lot out there on that topic. A helpful recent writer who brings together social ethics and Scripture is Glenn H. Stassen: Living the Sermon on the Mount: A Practical Guide to Grace and Deliverance (Jossey-Bass, 2006); with David Gushee, a Christian ethics textbook, Kingdom Ethics: Following Jesus in Contemporary Context (InterVarsity: 2003); and “The Fourteen Triads of the Sermon on the Mount: Matthew 5:21-7:12. Journal of Biblical Literature 122/2 (Summer, 2003), 267-308.