The Sermon on the Mount is the first of five great discourses in Matthew (chs. 5-7; 10; 13; 18; 24-25). It contains three types of material: (1) beatitudes, i.e., declarations or blessedness (5:1-12), (2) ethical admonitions (5:13-20; 6:1-7:23), (3) contrasts between Jesus’ ethical teaching and Jewish legalistic traditions (5:21–48). The Sermon ends with a short parable stressing the importance of practicing what has just been taught (7:24–27) and an expression of amazement by the crowds at the authority with which Jesus spoke (7:28–29).
Opinion differs as to whether the Sermon is a summary of what Jesus taught on one occasion or a compilation of teachings presented on numerous occasions. Matthew possibly took a single sermon and expanded it with other relevant teachings of Jesus. Thirty-four of the verses in Matthew’s Sermon occur in different contexts in Luke than the apparently parallel Sermon on the Plain (Lk 6:17–49).
The Sermon on the Mount’s call to moral and ethical living is so high that some have dismissed it as being completely unrealistic or have projected its fulfillment to the future kingdom. There is no doubt, however, that Jesus (and Matthew) gave the sermon as a standard for all Christians, realizing that its demands cannot be met in our own power. It is also true that Jesus occasionally used hyperbole to make his point (see, e.g., note on 5:29–30).
Concordia Self-Study Bible, New International Version, p. 1456