Luke 6 and Matthew 5

In that chapter, we find Jesus delivering his "Sermon on the Plain." In many respects it is much like the Sermon on the Mount. But we really don't have any way to know if it is or isn't the same occasion. It is possible that the two accounts might be reconciled as referring to the same event. Ancient Near-Eastern standards of quoting and reproducing material such as this were very different from modern Western standards. They did not consider an accurate paraphrase to be a misquote. Moreover, they did not consider a partial representation of what was said to be inaccurate. Both these sermons must originally have been much longer than the versions we find preserved in the Bible. Matthew and Luke did not record word-for-word transcripts. Rather, they provided summaries and examples of what Jesus said, both of which were selected in order to further the specific goals of their specific writings.

On the other hand, it is very likely that Matthew 5-7 and Luke 6 refer to different events. Remember, Jesus conducted a public teaching ministry for three years, and he had different crowds all the time. It is almost inconceivable that he did not deliver the same teaching content on multiple occasions, perhaps even using the same words in the case of formulaic statements or stock teachings. Teachers develop typical ways of teaching their material, and favorite subjects of teaching. Jesus was probably no different in this regard.

We cannot conclusively say that it was or wasn't the same event. But I'm not sure that it really makes a difference. If they are the same event, inerrancy is not challenged because of the freer nature of quoting and narrative presentation in ancient Near-Eastern literature.