Why is Matthew's gospel longer? Are the discourses verbatim?
Why is Matthew’s gospel longer? I don’t know. Luke’s is slightly longer than Matthew’s, although he leaves out most of two years of the life of Jesus, and concentrates on the last couple of months of his life. It may be that Matthew and Luke were naturally more verbose than Mark and John. It may be that Mark (who may have been taking dictation from Peter) just chose to concentrate on what Jesus did rather than what he said. It may be that John, writing several years after the other three, did not want to repeat what they had said. Or it may be that John picked incidents and conversations in the life of Jesus that specifically touched on a point he was trying to make with his whole book. All of this is speculation, although that last statement about John seems very likely.
Are the discourses in Matthew’s gospel word for word correct? As one who believes that the Bible is the verbally inspired word of God, I would have to say they are. Matthew and the other writers were aided by the Holy Spirit in remembering conversations exactly. Having said that, it is possible that the Sermon on the Mount (Matthew 5-7) is actually a compilation of several sermons Jesus preached. There is strong indication in the gospels that Jesus had several sermons that he repeated in different towns, just as my preachers do today. Even if it is a combination of several sermons, I still believe that it is a verbatim account of things that Jesus said.