I’ve been preaching through the Sermon on the Mount (Matt 5–7) this summer, and I’ve found myself coming back to three resources over and over again. If I had to pick only three commentaries, these would be the ones I’d pick. Together they cover the major technical discussions and the more difficult pastoral and ethical issues raised by the greatest sermon ever preached.
John Nolland, The Gospel of Matthew (NIGTC) — What you know and love from the NIGTC (detailed discussion of the Greek text), but Nolland does well not to get hung up in the minutiae and continues to highlight the major themes of the Sermon.
Jonathan Pennington, The Sermon on the Mount and Human Flourishing: A Theological Commentary — Pennington was one of my seminary professors, and I took a Sermon on the Mount class with him before this book came out. The book takes the material I learned and expands on it. Pennington argues that the Sermon is Jesus’ answer to the philosophical question: “How can we experience true human flourishing?”
Charles Quarles, The Sermon on the Mount: Restoring Christ’s Message to the Modern Church — By far, Quarles offers the most thorough discussion of individual pericopes. His work bridges the 2nd Temple context to today so that it has been the most helpful in the week-to-week preparation of my sermons.