He went up into a mountain. Those who think that Christ's sermon, which is here related, is different from the sermon contained in the sixth chapter of Luke's Gospel, rest their opinion on a very light and frivolous argument. Matthew states, that Christ spoke to his disciples on a mountain, while Luke seems to say, that the discourse was delivered on a plain. But it is a mistake to read the words of Luke, he went down with them, and stood in the plain, (Luke 6:17,) as immediately connected with the statement that, lifting up his eyes on the disciples, he spoke thus. For the design of both Evangelists was, to collect into one place the leading points of the doctrine of Christ, which related to a devout and holy life. Although Luke had previously mentioned a plain, he does not observe the immediate succession of events in the history, but passes from miracles to doctrine, without pointing out either time or place: just as Matthew takes no notice of the time, but only mentions the place. It is probable, that this discourse was not delivered until Christ had chosen the twelve: but in attending to the order of time, which I saw that the Spirit of God had disregarded, I did not wish to be too precise. Pious and modest readers ought to be satisfied with having a brief summary of the doctrine of Christ placed before their eyes, collected out of his many and various discourses, the first of which was that in which he spoke to his disciples about true happiness.

And seeing the multitudes - The great numbers that came to attend on his ministry. The substance of this discourse is recorded also in Luke 6. It is commonly called the "Sermon on the Mount." It is not improbable that it was repeated, in substance, on different occasions, and to different people. At those times parts of it may have been omitted, and Luke may have recorded it as it was pronounced on one of those occasions. See the notes at Luke 6:17-20.
Went up into a mountain - This mountain, or hill, was somewhere in the vicinity of Capernaum, but where precisely is not mentioned. He ascended the hill, doubtless, because it was more convenient to address the multitude from an eminence than if he were on the same level with them. A hill or mountain is still shown a short distance to the northwest of the ancient site of Capernaum, which tradition reports to have been the place where this sermon was delivered, and which is called on the maps the Mount of Beatitudes. The hill commonly believed to be that on which the sermon was delivered is on the road from Nazareth to Tiberias, not far from the latter place. The hill is known by the name of Kuran Huttin, the Horns of Huttin. Of this hill Professor Hackett (Illustrations of Scripture, pp. 323, 324) says: "Though a noontide heat was beating down upon us with scorching power, I could not resist the temptation to turn aside and examine a place for which such a claim has been set up, though I cannot say that I have any great confidence in it. The hill referred to is rocky, and rises steeply to a moderate height above the plain. It has two summits, with a slight depression between them, and it is from these projecting points, or horns, that it receives the name given to it. From the top the observer has a full view of the Sea of Tiberias. The most pleasing feature of the landscape is that presented by the diversified appearance of the fields. The different plots of ground exhibit various colors, according to the state. of cultivation: some of them are red, where the land has been newly plowed up, the natural appearance of the soil; others yellow or white, where the harvest is beginning to ripen, or is already ripe; and others green, being covered with grass or springing grain. As they are contiguous to each other, or intermixed, these particolored plots present at some distance an appearance of joyful chequered work, which is really beautiful.
"In rhetorical descriptions of the delivery of the Sermon on the Mount, we often hear the people represented as looking up to the speaker from the sides of the hill, or listening to him from the plain. This would not be possible with reference to the present locality; for it is too precipitous and too elevated to allow of such a position. The Saviour could have sat there, however, in the midst of his hearers, for it affords a platform amply large enough for the accommodation of the hundreds who may have been present on that occasion."
And when he was set - This was the common mode of teaching among the Jews, Luke 4:20; Luke 5:3; John 8:2; Acts 13:14; Acts 16:13.
His disciples came unto him - The word "disciples" means "learners," those who are taught. Here it is put for those who attended on the ministry of Jesus, and does not imply that they were all Christians. See John 6:66.

And seeing the multitudes - Τους οχλους, these multitudes, viz. those mentioned in the preceding verse, which should make the first verse of this chapter.
He went up into a mountain - That he might have the greater advantage of speaking, so as to be heard by that great concourse of people which followed him. It is very probable that nothing more is meant here than a small hill or eminence. Had he been on a high mountain they could not have heard; and, had he been at a great distance, he would not have sat down. See the note on Matthew 5:14.
And when he was set - The usual posture of public teachers among the Jews, and among many other people. Hence sitting was a synonymous term for teaching among the rabbins.
His disciples - The word μαθητης signifies literally a scholar. Those who originally followed Christ, considered him in the light of a Divine teacher; and conscious of their ignorance, and the importance of his teaching, they put themselves under his tuition, that they might be instructed in heavenly things. Having been taught the mysteries of the kingdom of God, they became closely attached to their Divine Master, imitating his life and manners; and recommending his salvation to all the circle of their acquaintance. This is still the characteristic of a genuine disciple of Christ.

And seeing the multitudes,.... The great concourse of people that followed him from the places before mentioned,
he went up into a mountain; either to pray alone, which was sometimes his custom to do, or to shun the multitude; or rather, because it was a commodious place for teaching the people:
and when he was set: not for rest, but in order to teach; for sitting was the posture of masters, or teachers, see Matthew 13:2 Luke 4:20. The form in which the master and his disciples sat is thus described by Maimonides (z).
"The master sits at the head, or in the chief place, and the disciples before him in a circuit, like a crown; so that they all see the master, and hear his words; and the master may not sit upon a seat, and the scholars upon the ground; but either all upon the earth, or upon seats: indeed from the beginning, or formerly, "the master used to sit", and the disciples stand; but before the destruction of the second temple, all used to teach their disciples as they were sitting.''
With respect to this latter custom, the Talmudists say (a), that
"from the days of Moses, to Rabban Gamaliel (the master of the Apostle Paul), they did not learn the law, unless standing; after Rabban Gamaliel died, sickness came into the world, and they learnt the law sitting: hence it is a tradition, that after Rabban Gamaliel died, the glory of the law ceased.''
His disciples came unto him; not only the twelve, but the company, or multitude, of his disciples, Luke 6:17 which he made in the several places, where he had been preaching; for the number of his disciples was larger than John's.
(z) Hilch. Talmud Torah, c. 4. sect. 2. (a) T. Bab. Megilla, fol. 21. 1. Vid. Misn. Sota, c. 9. sect. 15. & Jarchi, Maimon, & Bartenora in ib.

None will find happiness in this world or the next, who do not seek it from Christ by the rule of his word. He taught them what was the evil they should abhor, and what the good they should seek and abound in.

THE BEATITUDES, AND THEIR BEARING UPON THE WORLD. (Matthew. 5:1-16)
And seeing the multitudes--those mentioned in Matthew 4:25.
he went up into a mountain--one of the dozen mountains which ROBINSON says there are in the vicinity of the Sea of Galilee, any one of them answering about equally well to the occasion. So charming is the whole landscape that the descriptions of it, from JOSEPHUS downwards [Wars of the Jews, 4.10,8], are apt to be thought a little colored.
and when he was set--had sat or seated Himself.
his disciples came unto him--already a large circle, more or less attracted and subdued by His preaching and miracles, in addition to the smaller band of devoted adherents. Though the latter only answered to the subjects of His kingdom, described in this discourse, there were drawn from time to time into this inner circle souls from the outer one, who, by the power of His matchless word, were constrained to forsake their all for the Lord Jesus.

Seeing the multitudes. We gather from Luke, chapter 6, that the Lord passed the night in the mountain in prayer; in the morning he chose and ordained the twelve; he then came down to the plain, where he found a vast multitude, whom he taught.
Went up into a mountain. Thought to be the "Horns of Hattin," a mountain about seven miles south of Capernaum, near the Sea of Galilee.
When he was set. Eastern teachers usually sat while teaching.
His disciples came. Not the apostles only, but all anxious to learn and follow him. Disciple means a learner.

And seeing the multitudes - At some distance, as they were coming to him from every quarter. He went up into the mountain - Which was near: where there was room for them all. His disciples - not only his twelve disciples, but all who desired to learn of him.